John Gallagher, Jr. auditioned for a role in a previous film directed by James Gunn, but wasn't right for the part. However, Gunn thought he was the best actor he'd seen in an audition, and vowed to work with Gallagher again.
James Gunn was originally set to direct this film from his screenplay. However, when it was time to begin, Gunn withdrew, deciding he didn't want to spend several months working on such a violent film. He was also going through a divorce at the time. and withdrew from the project. He later said that he was surprised the movie was moving forward with Greg McLean as the new director. He was happy that he hadn't been asked again to direct, and he looked forward to seeing how McLean brought his script to the big screen.
The plot draws heavily from Battle Royale (2000). The trailers feature Giuseppe Verdi's "Requiem," which was also used in the Japanese film.
James Gunn wrote the first draft of the script in two weeks. Moreover, Gunn got the idea for the story from a dream he had.
James Gunn makes a point of putting serveral of the same actors in as many as his films as possible, including Sean Gunn (his brother), Michael Rooker, Gregg Henry and Stephen Blackehart, all of whom appear in this film.