Ron Shelton had originally written his directorial debut, Bull Durham (1988), for Kurt Russell over a decade earlier, but Orion wanted Kevin Costner for the role.
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.
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 footage of an anxious Kurt Russell in the hotel room was shot in one take, then intercut with itself and other scenes.