The Joker's Hard Times (2) - S2-E38
Continuity mistake: At GCPD HQ, when Commissioner Gordon decides to call Batman he removes the Batphone's acrylic dome cover and lifts the red receiver, still holding it when Joker shows up. Then, when Joker announces his next target is Libra the scales, in the next shot from a different angle, the Batphone is now untouched under the acrylic dome, between shots. (00:02:55)
The Joker's Hard Times (2) - S2-E38
Continuity mistake: After Joker enters Commissioner Gordon's office, Gordon and Chief O'Hara walk over to the window, and the Batphone table is behind them, beside Gordon's desk. Then Joker makes two "quick-frozen cops" and runs off to snatch Justice, leaving Gordon and O'Hara immobile. When their shock paralysis wears off, Gordon and O'Hara rush over to Gordon's desk, but the Batphone table and the Batphone have vanished (note the rug's pattern). (00:03:00 - 00:04:55)
The Joker's Hard Times (2) - S2-E38
Visible crew/equipment: After Joker and his henchmen steal the statue, it cuts to Commissioner Gordon and Chief O'Hara as they recover from their shock paralysis, and when they walk over to Gordon's desk, the wheel of filming equipment is visible at the right side of the screen. (00:04:55)
The Joker's Hard Times (2) - S2-E38
Revealing mistake: When Joker pays another visit to Commissioner Gordon and Chief O'Hara, Joker's holding his wand, and in the shots from outside the GCPD office window we can see the wire cable dragging behind Joker, which is attached to the wand and providing its power. During these shots, the actors' small white tape markers are also visible on the rug, beside the Batphone table. (00:03:00)
The Joker's Hard Times (2) - S2-E38
Continuity mistake: When the Joker directs Gordon and O'Hara to look at the statue of Justice, they look at it from a front view. But when Joker comes out of the Police building where he left them frozen, it's from behind the statue, rather than in front.
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