There is an actual band in Canada called the Wyrd Sisters who tried to stop the November 18th release of 'Goblet of Fire' in Canada because there is a band of the same name in the movie, but they lost their case.

Tom Riddle's day of birth and death that is on the grave had to be digitally changed, after the director knew that "Harry Potter and the Half Blood Prince" contains information about Riddle.

During the Yule Ball scene, the "Wyrd Sisters" are playing; they are portrayed by singer Jarvis Cocker (of Pulp) and John Greenwood (of Radiohead), on guitar. While not related, Cocker is a family friend of English singer Joe Cocker.

Dan Radcliffe had to spend six months training followed by 3 weeks training in a tank to film the underwater scene. It took so long because they had to film in small increments, because since Harry grew gills, Radcliffe had to hold his breath the whole time; he wasn't allowed to breathe out on film.

Mike Newell only received $1 million to direct 'Goblet of Fire', whereas Chris Columbus received $10 million plus a percentage of the gross to direct 'Harry Potter and the Philosopher's Stone' (2001).

In 2004, rumors circulated on the Internet that Rowan Atkinson and John Malkovich were considered for the role of Lord Voldemort. Both rumors were proven to be false; Malkovich was an odd topic of rumor since, as an American, he wouldn't have been able to audition in the first place.

Mike Newell decided against the original idea of separating the 734-page book into two films released several months apart, figuring he could still make it into a workable film by cutting some of the bulkier subplots.

The type of bug used to demonstrate the Unforgivable Curses is a tailless whip scorpion.