James Ellroy declared that he had nothing to do with this film. David Ayer entirely re-wrote his script and only preserved the names of some characters.
Towards the end of the film, when Officer Williams and Detective Keough are on their way to 12657 Juliet and hear the verdict of the Rodney King trial, Officer Williams is seen loading a shotgun. The shotgun is an Ithaca 37, also known as the "L.A.P.D. Special", a firearm specifically made for the Los Angeles Police Department.
The footage of an anxious Kurt Russell in the hotel room was shot in one take, then intercut with itself and other scenes.
Standing in the background during Eldon's briefing to the S.W.A.T. team is Peter Weireter, who really is LAPD S.W.A.T.
The script was set in the midst of the 1960s Watts Riots. James Ellroy updated the original story in 1992 after the request of Producer Caldecot Chubb for budgetary reasons, but asked that his name not be used to promote the movie after he had seen it.