1. Jim Carrey was originally supposed to play the lead role of Buddy the elf.
2. Forced perspective was used instead of CGI to make it look like Buddywas a giant.
3. Will Ferrell had a load of health problems due to all the sugar he ate while filming.
As a sidenote, those cotton balls Buddy eats in the doctor's office? Cotton candy:
4. Does the costume Buddy wears look familiar? That's because it's heavily inspired by the ones the elves wear in the claymation classic Rudolph The Red-Nosed Reindeer.
5. Gimbel's is actually a digitally altered version of the Macy's on 34th Street in New York.
6. Buddy's 12-second burp is not done by Will Ferrell. It's actually done by the same voice actor as Brain from Pinky and the Brain.
7. Will Ferrell actually worked as a mall Santa before his career took off. Chris Kattan (Saturday Night Life) was his elf.
8. Will Ferrell's reactions in this scene are totally genuine. Director Jon Favreau used a remote control to manually pop the jack-in-the-boxes in order to surprise Will Ferrell.
9. Jon Favreau also did the voice of Mr. Narwhal for the movie.
And he had another cameo as Buddy's doctor:
10. The actor who played Ralphie in A Christmas Story makes a cameo as an elf in the film.
11. Will Ferrell turned down $29 million to do a sequel to Elf.
12. The jack-in-the-boxes make the same noise as the laughing hyenas at the Magic Kingdom in Disney World.
13. And in case you forgot, Peter Dinklage also plays the real-world "elf" in the movie:
14. The raccoon that attacks Buddy makes monkey sounds instead of whatever sound a raccoon makes.
15. The infamous "throne of lies" scene had to be shot in one take, as the set was too extensive to rebuild for another shot.
16. Some of the sets for Elf, like Walter’s apartment and Gimbals’ toy department, were built in an abandoned mental hospital in Vancouver, the same hospital where New Line shot Freddy Vs. Jason.
17. People were so shocked to see Will Ferrell in costume walking around Central Park and the Lincoln Tunnel that several traffic accidents were reported.
18. Finally, while this may be heartbreaking, you need to know: There aren't that many buttons in the Empire State Building's elevators.
All facts via IMDB and the film's commentary.
This post has been updated to meet our attribution standards.