1. Mike Newell, who directed Goblet of Fire, was the first British director to work on the Harry Potter series.
2. Warner Brothers originally wanted to turn the book into two films.
3. In order to cut down on the book's length, Newell decided to get rid of anything that wasn't crucial to Harry's journey.
4. The film took a year to make.
5. Stanislav Lanevski, who played Viktor Krum, was spotted by casting agents visiting his school. He was running late for afternoon registration when the casting director saw him and asked him to audition. He didn't go to the audition because he thought it was a joke, but they remembered him and phoned him up later.
6. Katie Leung, who played Cho Chang, attended an open audition. Her dad saw an advert for the role on TV and convinced her to go along.
7. And Robert Pattinson, who played Cedric Diggory, was busy filming throughout casting for Goblet of Fire. Because of this, his agent arranged for him to meet Newall in advance.
8. Ralph Fiennes, who plays Voldemort, had to shave his head and armpits for the role.
9. His head and arms were painted with veins for every day of filming.
10. He wore prosthetics to cover his eyebrows, but most of his face was uncovered because he was concerned about too many prosthetics blocking his facial expressions.
11. Although his nose was going to be prosthetic, it was eventually decided that it should simply be digitally removed post filming. This meant that he had to film with coloured spots stuck to his head.
12. Voldemort's costume was made from many layers of very thin silk.
13. And it was Fiennes' niece who convinced him to take the part.
14. JK Rowling said that Hermione's Yule Ball reveal wasn't as amazing in the film as she had envisaged it because Emma Watson was already so beautiful.
15. Newall told Watson that she should think of walking down the stairs as Hermione's Pretty Woman moment.
16. However, Watson tripped down the stairs on one of her first takes for that scene.
17. Everyone who took part in the dance had to attend five dancing lessons.
18. But because most of them took place while Daniel Radcliffe was filming his underwater scenes, he never really picked it up. As a result, you never see a shot of Harry dancing below his waist.
19. In an ideal world, Radcliffe said he would have taken Scarlett Johansson or Natalie Portman to the Yule Ball.
20. It was Warwick Davis's idea that Professor Flitwick should stage dive during the band's set. He suggested it to Mike Newall as a joke. But Newall liked it, so it happened.
21. Set designers covered the Great Hall in Lurex, a very reflective material, in advance of the Yule Ball.
22. It took 90 people four weeks to complete.
23. Harry's underwater scene took six weeks to film.
24. And it required six months of training before filming even started.
25. Filming took place in a purpose-built 60-by-60 foot tank, that was 20 feet deep, in the studio.
26. It contained two and a half million litres of water.
27. It was not heated.
28. In total, Radcliffe spent 41 hours and 38 minutes under water. He knows because he had to keep a log.
29. He sometimes filmed under water for up to three hours at a time.
30. He sustained two ear infections while filming.
31. Watson was the only person who already knew how to scuba dive, because she'd done it in the Maldives and Mauritius before.
32. But the characters (Hermione, Gabrielle, Ron, Cho) who the Triwizard champions had to rescue from the lake were actually dummies.
33. Watson fell flat onto her back four times during filming the campsite scene at the start of the film.
34. The character Nigel does not appear in the book at all.
35. When Cedric Diggory collapses in the maze, he literally had ropes tied to him to pull him into the ground.
36. Rosamund Pike turned down the role of Rita Skeeter.
37. The scene in which Rita Skeeter photographs Harry and Hermione hugging had to be filmed six times.
38. Alan Rickman, who played Professor Snape, wore contact lenses with some red in them for filming.
39. And Michael Gambon, who played Professor Dumbledore, wore tracksuit bottoms under his costume.