The Duo Is Slumming (2) - S2-E32
Visible crew/equipment: When Puzzler and his high-flying flunkies exit the shed it cuts to the Retsoor in Knab's hangar, and a few chalk T-marks become visible on the ground near the nose of the plane. (00:19:40)
The Duo Is Slumming (2) - S2-E32
Other mistake: While Batman and Robin are ascending in the balloon, Robin picks up a chewed piece of gum, and stops the altimeter just before 20,000 feet. After that, Robin wondered how to get down. Beside Batman's head is the handle of the cord that would have started to let the air out, and started dropping them down.
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