Twilight Zone - Twilight Zone, Season 3, the Trade-ins (1962)
This slip-up relates to the Twilight Zone Season 3 episode "The Trade-Ins", as the character named Mr. Holt (and his wife) are being shown (by a salesman) down a hallway of alcoves containing replacement bodies that are locked in stasis. As Mr. Holt and his wife move towards the left side of your TV screen to look at yet another set of bodies, the woman sitting in the alcove (possibly thinking that the camera has completely moved away from her) clearly moves her arm (visible in the upper right of the TV screen). You'll see the stasis woman, then Mrs. Holt passing by, then the movement of the stasis woman. Pretty obvious mistake if you're looking for it, but since the focus tends to be on the conversation between the salesman and Mr. Holt, I can see how it would be missed.
None -- just a television