Continuity mistake: Tied to a conveyor belt, Batman and Robin move past a stack of boxes stenciled with the factory's name. Cut to close-up, and they're now back to a position right next to the boxes. Back to master shot, and the boxes are once again several feet away - at least until the next close-up. (00:02:50)
Visible crew/equipment: When Harry plots to replace Chandell, the polished grand piano behind him reflects the moving lights on some of the studio equipment. (00:15:30)
Continuity mistake: Batman folds up the Bat Shield and starts to tuck it into his belt, which it is much too large to fit into. In the very next shot, the shield has disappeared. (00:21:00)
Answer: There wasn't one singular city used. It was shot in and around various locations in California, plus on a lot of sets and backlots. Ex. Some scenes were shot in LA, some in Pasadena, some in Santa Barbara, etc.
TedStixon