In 2001, Mark Wahlberg and Hugh Jackman were in talks to star. Production was scheduled to begin in February 2002. But after the September 11, 2001 attack on New York City and the celebrated heroics of the city's police, it was deemed inappropriate to make a film featuring corrupt NYPD officers at the time.
The trivia item below may give away important plot points.
Jimmy's (Colin Farrell) death scene was originally supposed to have Ray (Edward Norton) let him go into the crowd to be accosted by the angry mob and then the audience would assume that he died. Gavin O'Connor knew he needed a more powerful ending and that is when he decided to have Jimmy be beaten to death in front of Ray to add a sort of sympathy for the character Jimmy.