Amanda Alch, who plays the nerd, Megan, did the classroom strip scene wearing pasties. She then came back after the scene was shot to have her nipples photographed so they could CG her own nipples back on her breasts in post production. So, although people claim that the nudity wasn't real in the movie, what you see is actually the real thing! The movie's Twitter account did a funny story about it in April to promote the DVD release.
The movie is based on a best selling indie comic book series that had fans go to a "You Cast The Movie" section of its website to offer casting suggestions for the movie. Celebrities such as, Ben Browder, Judd Nelson, Marc Donato, Chanel Ryan, and Ali Faulkner, were selected to play roles in the movie, as a result.
Judd Nelson was cast as Headmaster Nash as an acknowledgment of the similarities between this film and The Breakfast Club (1985). Ironically, the character of John Bender from Breakfast Club is a bad boy, and in this film Judd's character disciplines bad boys and speaks of them quite harshly.
Fans of the comic book series who followed the creators to signings and conventions around the US, Canada, and the UK, suggested "bad kids" who helped promote the BKGtH franchise at comic-cons be given roles in the movie on the "You Cast The Movie" portion of the BKGtH website. As a result, the producers gave them opportunities to audition for the movie and even selected a few for cameos and supporting roles in the movie.
Most interior shots were filmed in a sound studio in Austin, called Spiderwood. Other shots, including exterior ones, were filmed in the Dallas area at parochial private schools and a synagogue, including a Catholic prep school, a Jesuit prep school, a Methodist university.