A Riddle a Day Keeps the Riddler Away (1) - S1-E11
Visible crew/equipment: While King Boris is being held as a pawn by Riddler, when Batman and Robin show up the duo jump over a crate, and the chalk T-mark is visible on the floor by Robin's feet. (00:21:05)
A Death Worse Than Fate (2) - S1-E10
Visible crew/equipment: When Zelda releases blindfolded Harriet at the street corner, there are two curved chalk actors' marks on the ground beside Harriet's feet. (00:08:35)
Visible crew/equipment: At the diamond exchange, when Mr. Freeze and his goons are by the wall safe, the shadow of the boom mic is visible in the top right corner of the screen. (00:13:50)
Visible crew/equipment: When the museum closes early and Joker calls to each of his cohorts, their individual chalk T-marks are visible on the floor where they all stand. (00:12:40)
The Penguin's a Jinx (2) - S1-E4
Visible crew/equipment: When Penguin is riding the large umbrella across the Penguin line in the wide shot, just as he is about to reach Dawn's terrace, we can see a crew member's two arms reaching out to Penguin and the top of a ladder, at the lower left side of the screen. (00:13:50)
Fine Feathered Finks (1) - S1-E3
Visible crew/equipment: In Commissioner Gordon's office, when Gordon is looking over the paperwork of three new umbrella factories, frustrated that none are in the name of Penguin, as he stands up we see two white tape marks on the rug behind him. In the previous scene with Warden Crichton, four of the actors had been standing in that area. (00:11:35)
Visible crew/equipment: When Minstrel and his henchmen race down the stairs, the sound pole rigging shadow is moving at the very top of the screen. (00:04:00)
Batman Stands Pat (2) - S1-E14
Visible crew/equipment: When Mad Hatter is sending Lisa in to butter up Mr. Bowinkle, the microphone shadow is bobbing up and down above their heads. (00:11:25)
The Yegg Foes in Gotham (2) - S2-E14
Visible crew/equipment: During the final egg fight, the microphone shadow puts in an appearance on the wall behind the bad guys. (00:21:50)
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)
The Devil's Fingers (1) - S2-E15
Visible crew/equipment: When Commissioner Gordon calls Chandell to reassure him that Batman and Robin are back in action, Chandell shares more root beer with Harriet. Then, when he hints for her to leave, a T-mark taped to the floor is visible at the lower left side of the screen. (00:18:20)
The Zodiac Crimes (1) - S2-E37
Visible crew/equipment: Bruce Wayne and Dick Grayson walk into the study alone when Bruce takes the Batphone call from Commissioner Gordon, then just as Bruce says, "The Joker again," at the top of the tuba bell we can see the reflection of a man wearing a white short-sleeved shirt and grey pants. Numerous studio lights are reflected as well. (00:03:15)
The Bird's Last Jest (2) - S2-E28
Visible crew/equipment: At the abandoned Navy rec center, when Penguin and his miscreants are out of bullets they surrender, and as they all gather with their hands up, there are a few chalk T-marks visible on the ground where they stand. (00:05:25)
The Thirteenth Hat (1) - S1-E13
Visible crew/equipment: When Hatter is at Octave Marbot's studio posing as him, Batman and Robin arrive, and chalk T-marks are visible on the floor near Batman's statue in the studio. Then while Batman is in the dressing room, Hatter quietly opens the studio's front door, and more chalk T-marks are visible on the floor in the hall. (00:18:40)
Batman Stands Pat (2) - S1-E14
Visible crew/equipment: When Batman and Robin use the Batmobile's Detect-a-scope to locate Turkey's bowler, as Batman notes that Hatter's hideout must be in the old warehouse, the reflection of the boom pole/mic is visible at the right side of the Batmobile's bubble windshield. (00:16:55)
The Entrancing Dr. Cassandra - S3-E25
Visible crew/equipment: While Batman and Robin are at GCPD, Batman decides to use the library to research occult sciences, and when it cuts to Cassandra and Cabala returning to their hideout they walk over to the table, and behind them we can see the chalk marks on the floor by the door, where they previously stood. (00:05:15)
Catwoman's Dressed to Kill - S3-E14
Visible crew/equipment: At GCPD, when Commissioner Gordon wonders how to catch Catwoman before she wreaks even more havoc, at the start of the next shot just as Barbara stands up, the boom mic casts a shadow on the wall as it moves, on the left side of the screen. (00:05:05)
The Foggiest Notion (2) - S3-E12
Visible crew/equipment: When Batgirl enters the cricket pavilion at Ffogg Place, two chalk T-marks are visible on the floor between the snuffboxes case and the diamonds case. (00:11:35)
Visible crew/equipment: After the first couple of shots of the Batcopter, when it cuts to Mr. Freeze at his refrigerated refuge, the two black tape marks are visible on the floor near Professor Isaacson's and Glacia's feet.
The Catwoman Goeth (2) (a.k.a. A Stitch in Time) - S2-E34
Visible crew/equipment: While Batman stands outside the run down factory, the GC rookie officer asks, "Who's Robin?" and both GC officers get back into their patrol car. Then as they drive away the reflection of equipment (looks like the boom pole) becomes visible on the vehicle's rear passenger window. Then it cuts to Batman, and the reflection of the boom pole is visible on the Batmobile's windshield, at the bottom right corner of the screen. (00:12:25)
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