Many cast members were fans of the books before starring in the films.
The first three “Harry Potter” books were published before filming began for the first movie, “Harry Potter and the Sorcerer’s Stone,” so plenty of cast members had already read them.
Emma Watson, who played Hermione, said her father used to read the “Harry Potter” books to her and her brother, and they were “obsessed” with them.
Matthew Lewis, Alfred Enoch, and Evanna Lynch all spoke about how much they loved the books as well.
The actors who play Fred and George, James and Oliver Phelps, especially enjoyed reading the parts with the Weasley twins.
“We instantly related to Fred and George because they aren’t many twins in literature,” James said during the reunion special.
Director Chris Columbus flew all the way to Scotland to pitch his vision for the first movies.
Chris Columbus’ daughter tried to convince him to read the “Harry Potter” books several times before he actually sat down with them.
But when he finally did, the director was inspired to work on the films.
“Immediately I saw the movies. I just saw them,” he said. “And that hasn’t happened since.”
Columbus even traveled all the way to Scotland to pitch his vision to the series’ controversial author, J.K. Rowling.
Casting Harry Potter ended up being a pretty big struggle.
Columbus described the casting search for Harry Potter as “insane.”
“We just couldn’t find Harry,” Rowling said in a prerecorded clip included in the reunion special, adding that they were getting “panicky.”
But when Columbus saw “David Copperfield” (1999), which featured a young Daniel Radcliffe, he immediately wanted the actor to audition.
Radcliffe’s parents initially refused because they didn’t want their son to deal with the pressure of such a huge commitment. But luckily they agreed to let him audition after a little convincing from producer David Heyman.
The Phelps twins made last-minute costume changes for their auditions.
Fred and George Weasley wear several matching and coordinating outfits throughout the “Harry Potter” series, but the Phelps twins didn’t initially think to do the same when they auditioned for the roles.
“We realized that we were the only set of twins who weren’t wearing identical clothing,” Oliver said. “We ended up going over the road and bought two identical, matching tops … just off the rack.”
Getting the young cast to focus during the first movie was challenging at times.
Robbie Coltrane, who played Hagrid, said that Columbus was great at working with children.
“Columbus had worked with kids a lot, and he was terrific with them. He really was.” Coltrane said. “He used to go down on his knees to talk to them and huddle around so nobody could hear.”
But as Lewis, who played Neville, pointed out, “It’s not easy cause it takes a tremendous amount of patience with kids — particularly with kids as hyperactive and as excitable as we all were.”
Several stars marveled at the fact that the director let them have fun and “just be kids” on the set.
“They probably made their jobs harder for themselves by letting us have as much fun as we had because it distracted us from the work we were supposed to be doing,” Radcliffe said.
The younger cast members didn’t seem to realize they were working with iconic actors.
Draco Malfoy actor Tom Felton said that the young cast was essentially unknowingly surrounded by the “cream of the British acting industry.”
“I thought Richard Harris worked here as a tour guide for a while,” Felton joked.
Columbus added, “I don’t think any of the kids had the capability of understanding the gravity of who they were dealing with at the time … The British royalty of the acting world.”
But on a set filled with children, Watson said that the legendary adult actors were the ones who “came in and were like the mischief” — Coltrane in particular, who Grint described as “such a kid.”
They originally used practical effects for the floating candles in the Great Hall, which ended badly.
The floating candles above the tables in the Great Hall are a charming part of the iconic set.
To make the candles appear to be floating, they were originally suspended from the ceiling on clear fishing wire — until they became a fire hazard.
“One of my favorite moments on set ever was the moment when all the floating candles started burning through the ropes that tied them to the ceiling and just started falling around the Great Hall,” Radcliffe said.
The actor added, “So much of that would be visual effects now. The fact that we got to actually be on that set … thank you, Stuart Craig.”
Craig was the production designer who brought many of the original “Harry Potter” sets to life.
One of the challenges of the films was figuring out how to portray quidditch on screen.
“The hardest scene to shoot was quidditch, and the audience had to understand the rules immediately,” Columbus said.
Luckily, Rowling created a sort of quidditch rule book for them that explained “every detail of the game.”
Craig then designed a pitch for the game that felt “authentic.”
Jason Isaacs originally auditioned for a different role.
Jason Isaacs played Lucius Malfoy, but he originally auditioned for the role of Gilderoy Lockhart.
He explained that since he was already set to play Captain Hook in “Peter Pan” (2003), he didn’t want to play another children’s villain. But Columbus asked him to read for the role anyway.
“I’m convinced I ended up playing Lucius because I didn’t want to,” he said. “… I read through gritted teeth, I was deeply bitter. And of course, that was exactly what was necessary, and they asked me to play Lucius, and thank God they did.”
He later found the role “ridiculously good fun.”
Felton found it jarring to work with Isaacs at times, and he was even minorly injured by his on-screen father.
Isaacs had plenty of scenes with young Felton, who he described as “the biggest sweetheart.”
But Felton found Isaacs’ ability to suddenly get into character a bit jarring.
“He just immediately turned into the most unfriendly, horrible person I’ve ever met,” Felton said. “He’d be this evil father and then they’d say cut, and he’ll come and give you a cuddle …”
Isaacs said that during the first scene he shot, he had to swat his snakehead cane at Draco, and he accidentally cut his on-screen son’s hand.
“He looked up at me and his eyes welled with tears, and I went, ‘Tom I’m so sorry … ‘ and he went, ‘It’s all right, it’s good for the scene,'” Isaacs said.
Richard Harris thought the animatronic used for Fawkes the Phoenix was a real bird.
Richard Harris, who was the first person to play Dumbledore, was one of the legendary actors the young cast had the opportunity to work with. But Radcliffe and Columbus recalled a time on set when Harris wasn’t exactly aware of his surroundings.
“You and I had one of our greatest laughs together with Richard Harris, and we had an animatronic version of Fawkes the Phoenix … Richard came in and looked at the phoenix and said, ‘Wow they train these animals marvelously these days,” Columbus said to Radcliffe during the reunion.
Radcliffe explained that there was a camera in the bird’s eyes, so the operator would realistically follow the actor around when he looked at Fawkes.
“We never told him,” Radcliffe said.
Columbus said he “always felt guilty” about leaving the cast after the first two films.
During the reunion special, Radcliffe told Columbus, “I do not know of another human being who could’ve started the series in the way you did.”
But, as Columbus told The Hollywood Reporter in 2021, he was “emotionally and physically exhausted” at the time and felt like he was missing out on time with his own children. The director left the series after the second film.
“I’ve always felt guilty about leaving. I really did. When I said goodbye to you guys, I was like, I can’t believe I’m leaving these guys,” Columbus told Radcliffe.
Gary Oldman was the first actor in the series who Radcliffe was a bit starstruck by.
Despite having spent the first two movies around plenty of esteemed actors — like Harris, Coltrane, Maggie Smith, and Alan Rickman — Radcliffe wasn’t really starstruck until Gary Oldman joined the cast of “Prisoner of Azkaban” as Sirius Black.
“The first person I remember being like in awe of when they came in was Gary,” Radcliffe said.
“I remember you giving me the Gary chat,” Watson told her costar. “You were like, ‘Listen Emma, you need to be cool because Gary Oldman, it’s a really big deal, and you need to be cool.'”
Radcliffe called that “a projection of his own fears” of the incredible actor coming to set.
“Prisoner of Azkaban” director Alfonso Cuarón called Radcliffe and Oldman’s relationship “sweet” and said it mimicked Harry and Sirius’ from the series.
Rickman may have been the only actor who knew his character’s arc ahead of the book releases.
The “Harry Potter” books were still being written when the first movies came out, so the cast didn’t know how their characters’ arcs would end.
Radcliffe said that Rickman had “the inside line” because he convinced Rowling early on to tell him what happens to Snape.
Rickman never shared Rowling’s plans for his character with the rest of the cast, or even the directors.
Cuarón assigned homework to the main trio, which they each dealt with in ways that fit their characters.
Watson said that when Cuarón first started on the third movie, there was a shift from Columbus’ style. For one, Cuarón assigned the now-teen actors homework.
Rupert Grint, who played Ron, explained that the director told him, Watson, and Radcliffe to write about their characters so he could get a better feel for them.
Radcliffe wrote about half a page, Watson wrote about 12 pages, and Grint never turned in the assignment, which all seemed very fitting for Harry, Hermione, and Ron.
The George Weasley actor accidentally broke a few of director Mike Newell’s ribs on set.
In “Harry Potter and the Goblet of Fire,” the Weasley twins fight each other after a failed attempt at entering the Triwizard Tournament.
Director Mike Newell, who worked on the film, stepped in to demonstrate what the interaction should look like by fighting with Oliver.
The director said he “really shouldn’t have done it” because he ended up cracking a few ribs, leaving him in “absolute agony” for the rest of filming.
“You know when you shouldn’t break a director’s rib?” James chimed in, pointing at his brother.
Plenty of the cast had their first crushes and relationships on set.
Bonnie Wright, who played Ginny Weasley, said the fourth movie was “all about teenagers having crushes for the first time,” which was relatable for the young cast.
“We were literally having the same experiences,” she said.
Radcliffe and Watson said they even gave each other dating advice on set, and Radcliffe described “Goblet of Fire” as “peak hormone” for him.
Lewis also explained that there were crushes and relationships on set, much like there would be with kids their age at school.
The Phelps twins convinced Grint that he missed learning an entire dance routine for the fourth movie.
In “Goblet of Fire,” a big portion of the plot centers on the Yule Ball.
Before they shot the scene where Professor McGonagall holds dance lessons for the students in the lead-up to the event, the Phelps brothers convinced Grint that he was supposed to learn a big dance routine for the scene.
“We were winding him up,” James said.
“We were like, ‘Do you know your steps?'” Oliver added. “‘You know, the routine? We’ve all been doing a routine for the past like six weeks.'”
The pressure of Hermione’s dramatic Yule Ball entrance bothered Watson.
Watson discussed the importance of Hermione’s Yule Ball entrance scene, saying that it marks the first time Harry and Ron both see her as a young woman and not just their sidekick.
“I knew it was a big deal, and I was miserable,” she said. “I just knew that it was the like duckling-becomes-a-swan moment. I knew that there was just like all of this pressure suddenly.”
She added, “Of course, I fell down the stairs.”
Though Watson and Felton have never been involved romantically, the two both expressed their love for each other.
Watson had a crush on Felton during the earlier movies, which Felton was aware of, and she remembered exactly when it started.
They were asked to draw what they thought God looked like during a tutoring session on the set of an early film, and Felton drew a girl with a backward hat on a skateboard.
“I just don’t know how to say it, I just fell in love with him,” Watson said.
She said she would excitedly look for his number (seven) on the call sheet every day, but she also knew he saw her more like a little sister.
Felton, who’s three years older than Watson, said he felt very protective of her.
“Yeah, I’ve always had a soft spot for her, and that continues to the day,” he added.
“Nothing has ever ever ever ever happened romantically with us,” Watson clarified. “We just love each other.”
Radcliffe essentially wrote Helena Bonham Carter a love letter during the fifth movie.
During the reunion special, Helena Bonham Carter, who played Bellatrix Lestrange, brought a photo of the autograph Radcliffe wrote for her during the fifth movie.
After throwing in an inside joke from their time on set, he wrote, “I do love you, and I just wish I’d been born 10 years earlier, I might have been within a chance. Lots of love and thanks for being cool.”
The actors laughed about the exchange, and Bonham Carter said she will “always treasure that.”
The scene where Bellatrix kills Sirius was originally supposed to be longer.
In the fifth film, Bellatrix kills Sirius when she catches him with a spell and he falls behind the Veil between the living and the dead.
Bonham Carter called the scene a “real jewel,” and Oldman said they spent several days on set shooting things that were fully cut.
Watson wasn’t sure she wanted to continue with the series after the first four films.
Watson, who was younger than many of her costars, considered leaving the films after the fourth movie when “the fame thing had finally hit home in a big way.”
“I could see that at the time, I was lonely,” she said. “… I think I was scared.”
Radcliffe said they never talked about grappling with young fame when they were on set.
“As a 14-year-old boy, I was never going to turn around to another 14-year-old and be like, ‘Hey, how are you doing? Is everything OK?'”
Grint said he also had moments where he’d realize the enormity of what they were working on and consider what it would be like to leave. But he hadn’t realized Watson was feeling the same way.
In the end, Watson said, “No one had to convince me to see it through. The fans genuinely wanted you to succeed and we all genuinely have each other’s backs. How great is that?”
Watson’s hamster died while they were filming, and the set designers made her a real coffin.
Like some of the Hogwarts students who carried cats, owls, and toads with them to school, Watson said she had a pet hamster named Millie on set.
Unfortunately, Millie died while they were still filming, but Watson said the set designers “built Millie her own custom-made wooden coffin that had velvet on the inside … and it had her name engraved because I was beside myself.”
She also said that she kept getting the urge to pick up the dead hamster, and the set designers had to convince her to leave Millie in the coffin.
The stars said losing fellow cast members has been like mourning family members.
Watson said it was “shocking” that so many cast members have died since the movies were made, and Grint noted that grieving those cast members was like grieving family.
Harris, Richard Griffiths, Rickman, John Hurt, and Helen McCrory are among the main stars of the series who have died.
Radcliffe said losing Griffiths, who played Uncle Vernon, affected him the most because the actor was “generous” in sharing knowledge with him on set.
Isaacs called McCrory, who played his on-screen wife Narcissa Malfoy, “the best actress” he’d ever met. And Felton teared up when talking about how much she taught him.
Watson also added that Rickman always took her seriously, which she appreciated.
The kiss between Ron and Hermione was incredibly difficult to shoot.
The eighth film shows Ron and Hermione’s first kiss, which Watson called “the most horrifying thing” to film.
Director David Yates knew the moment was important to viewers, who’d been waiting for the kiss for years, but Watson and Grint were struggling to get through it without laughing.
Radcliffe apologized for having made things worse by being “an absolute dick” about the scene.
“I did not make this better … I was like, ‘I’m gonna come on set and watch you guys kiss,'” Radcliffe said.
The actors were able to get the scene done after Watson took initiative, though she said kissing Grint was like kissing a sibling.
“I kind of think I blacked out,” Grint said to Watson, “I just remember your face getting closer and closer.”
“Kissing Rupert is one of the hardest things I have ever had to do,” Watson added. “It just felt wrong, so wrong on every level.”