The Decapod - S2-E3
Revealing mistake: In the midst of Steed's conversation with the wrestling referee, the camera loses focus and suddenly whip-pans away when it shouldn't. The actors continue their lines as the camera comes quickly back and refocuses on them. (00:19:45)
Revealing mistake: The secretary turns on the tape recorder to play back her employer's dictation. His voice starts speaking, but the tape reels aren't turning, and the button she pushed hasn't stayed depressed. Apparently, the machine isn't even on. (00:01:20)