Producer Peter McCarthy persuaded John Cusack, with whom he had worked before, to appear in the last big shoot-out scene as a delivery boy. He was shot multiple times and was burned by several of the nearly 20 squibs attached to his body. They didn't use the scene.
When Slammer asks Jack Spade, "What makes you think you can be a black hero?", Spade responds by saying, "I'm an ex-football player." Jim Brown played football for the Cleveland Browns from 1957-1965, and is in the NFL Hall of Fame. Bernie Casey and Fred Williamson were also professional football players before becoming actors.
During the altercation scene with Mr. Big, Mr. Big declared that this film will never have a sequel. Mr. Big's statement is prophetic indeed because as of 2016, there hasn't been any talks nor plan in making a follow up to this movie.