Revealing mistake: Near the end of the episode, all the castaways are passed out cold when Lord Beasley finally catches his butterfly. Right after saying the line "That's the trouble with you Americans - you simply don't know how to hold your tea" as he's exiting off camera, Mrs. Howell starts to open her eyes slightly, but then quickly shuts them again. Perhaps she thought the cameras stopped rolling.
Double, Double, Toil and Trouble - S4-E4
Revealing mistake: As Serena gets hit by the pie her real blonde hair shows underneath, also, she wears minimal make-up for the only time.
Revealing mistake: When the dummy plane is shot out of the sky by the fighter pilot, a piece of the plane shoots off into the top left of the screen and bounces off the sky background. (00:23:05)
Revealing mistake: After the car hits Herman, it falls apart. After the left front tire falls off, the prop holding up the frame is plainly visible.
Revealing mistake: The switch that Phones uses to turn off the television set is labelled "BRIGHTNESS".
The Addams Family Meet the VIPs - S1-E11
Revealing mistake: After Mr. Harris leaves the play room, Fester goes to lay down on the bed of nails. As he does, the squared outline of the board under his robe he lays on is visible.