Factual error: When Riddler's rocket hits the Batcopter, the villains are watching from the periscope as Batman and Robin are crashing. However, the image they see is a straight-on shot, as if the lens were right in front of the copter. No pre-atomic periscope can reach that far up.
Audio problem: As the camera looks at the delegates, it gets to the Japanese man. What is heard in no way matches his mouth's movements. Also, the British representative can be heard speaking a second or two after disappearing.
Other mistake: When spying on Bruce and Kitka, the view that Robin has is the movie camera view, which would be impossible.
Continuity mistake: When the officials are being dehydrated, close ups of the liquid in the dehydrater show the level increasing up to about 75% but far away shots show the level steady at about 20%.
Continuity mistake: Before the final torpedo, the projector lenses are out. After the explosion, the Batboat is gone, and the projector is again concealed. Batman didn't have time to put the cover on.
Visible crew/equipment: As the Bat copter is approaching the yacht, in the frame is a crew member, either a member of the yacht's crew...or production crew. He apparently realises he is on camera and ducks down behind a railing.
Continuity mistake: Toward the end of the fight scene on the deck, knotted ropes suddenly appear.
Revealing mistake: As the camera watches the duel between Batman and Penguin, the wall of the set is painfully obvious, as you can see lines and ripples in the scenery of the sky.
Continuity mistake: After Robin gets rid of a goon, Joker comes toward him. After Joker misses with a swing, Robin pops him and he starts to go overboard. A second later he goes over again.
Revealing mistake: After hitting the Riddler and Joker, a thug with the red and white striped cap goes to hit Batman. As he does, Batman starts to turn away from the oncoming punch well before the man's fist is even near him.
Continuity mistake: When boarding the sub, Robin ties the Batboat off to keep it in place, but it disappears when the fight breaks out. Also, they come aboard well aft of the forward hatch, but a moment later, they're just a couple feet away from it, walking towards the Conning tower.
Continuity mistake: As Joker uses the dehydrator, the amount of water in the container varies between shots from almost empty to almost full and back.
Other mistake: After opening the abandoned elevator, the Penguin tells his cohorts to hold their breaths because of lingering gas, and there was no real sign of it. However, before the elevator, there was colored gas all over, and he walked through with no ill effects, and held his breath with the others.
Audio problem: After Guinea Pig 4 disappears, the camera looks at Riddler and Catwoman. You hear Riddler giggling, but he has an astonished look on his face for a second and then giggles.
Visible crew/equipment: As the Batboat preps to leave, the rotor wash of the camera chopper is visible playing across the water, and as it takes off, the blades of the chopper are visible as it tries to catch up to the boat.
Revealing mistake: As the Batmobile approaches the camera on the pier, the tire tracks from a previous take are visible on the deck boards, and as the Batmobile nears, it follows the tracks precisely.
Other mistake: When the shark falls away from the ladder, the hook used to hold it in place is visible.
Revealing mistake: When Robin is trying to get the sub to surface using Bat Depth Charges, the sub is rocking violently. The rack that contains the vials with the Security Council's dust not only sways back and forth, but lies nearly flat several times, and always at impossible angles. This goes against physics, and gravity. The rack should have fallen off the table more than a few times.
Revealing mistake: Whenever you see the underwater shots of the sub, and the torpedoes, you can see the sides of the pool where the filming was done.
Answer: The timeline of the movie is important to consider. The 1966 film began production while season 1 of the TV series was being aired. Eartha Kitt didn't play Catwoman until season 3. According to the TV show "Biography", Newmar was suffering from a back injury and unable to reprise her role for the movie. But she was able to recover by the time they started shooting the 2nd season. So, for the movie they hired Meriweather.
Bishop73