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)
Other mistake: When Mr. Freeze is moving through the room evaluating the diamonds, the tanks on his back can be fire extinguishers. There is no way that the "weapon" attached by hose to them will work, as the handles have to be squeezed to discharge.
Answer: It's wasn't unusual for multiple actors to play one character on this show. The villains on the TV Batman were played by guest stars, not regular cast members. George Sanders, Otto Preminger, and Eli Wallach played the part at various times. They may simply have only wanted to play the part once or twice, or they were later tied up with other projects, making it necessary to cast someone else. Other characters, like Catwoman, were also played by more than one actress.
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