Every studio in Hollywood turned down Ebbe Roe Smith's script. Producer Arnold Kopelson was getting to the stage of considering cable TV when Michael Douglas came across the script and pronounced it one of the best he'd ever read.
In the scene in which the drive-by car crashes, there is a mural of Christ on the wall. This same mural is also present in Colors (1988), also starring Robert Duvall, in the scene in which the police officer played by Sean Penn, spray paints a kid's face.
"London Bridge is Falling Down" is heard several times in the film. Prendergast (Robert Duvall) sings "London Bridge" with his wife (Tuesday Weld) on the telephone. The same tune is played by the snow globe that D-Fens buys on Wilshire. The lyrics to the song are "London Bridge is falling down, falling down", a reference to the movie's title. A bridge appears on the retirement cake of Det. Pendergrast then moments later, he punches Detective Lydecker (D.W. Moffett) who falls into the bridge. Prendergast also planned to retire to Lake Havasu, Arizona, where the old London Bridge was moved to in 1971.
The Korean American Coalition protested the film for its treatment of minorities as well as the Korean grocer. Because of this and the boycott threats that followed, this movie was banned in South Korea.
The trivia items below may give away important plot points.
As Bill Foster gets closer to home, the weapons he acquires become more lethal as do the people from whom he acquires them; First, he acquires a bat from the store owner, then a butterfly knife from the gang member, minutes later an Uzi from the same gang members car and finally a rocket launcher from the skinhead.