The Zodiac Crimes (1) - S2-E37
Revealing mistake: When Joker enters Commissioner Gordon's office at GCPD, he's pointing a wand at Gordon and Chief O'Hara. In the shot facing Joker when he lets go of the wand, the wires at both ends of the wand are visible. (00:01:15)
The Zodiac Crimes (1) - S2-E37
Revealing mistake: After Joker's goons kidnap Crustash, the opera singer, Penguin tries to sneak off, and when Batman and Robin use javelins to capture Penguin, the glistening stunt wire attached to the javelin is visible in the wide shot. (00:18:15)
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