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)
The Four-Steps Affair - S1-E21
Revealing mistake: Solo is driving on a country road through a wooded area with no street lights. So what are all those bright round lights reflecting on the hood and windshield of his car? UFOs? (00:10:10)
Revealing mistake: While the Seaview rocks violently back and forth from the concussion of the under water explosion, the pencils, folders, papers, etc., on the navigation table do not move.
How to Succeed in Farming Without Really Trying - S3-E6
Revealing mistake: When the patroon is policing the area, raking and sweeping, they are not really raking or sweeping. They are just going through the motions but the rake and brooms are not touching the ground. (00:06:00 - 00:07:00)
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 footage of the assassin climbing up the drain pipe and leaping across the rooftop at the beginning of the episode is reused from the episode "A Room in the Basement." You can even see Drake already up on the roof from that episode, whereas there's only one person climbing in this one. (00:00:30 - 00:00:40)
The Thanksgiving Story - S2-E10
Revealing mistake: The close ups of Daniel and Jericho on the wagon show a pale blue background but the long shots show them on a heavily wooded trail crowded with large green trees behind them.
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.
Revealing mistake: When Malot lunges against the cage holding Savage, the "iron" bars bend inward. (00:30:25)
Revealing mistake: At the very beginning of the episode, we see a hydrocharge being fired which causes an explosion in the sea. Then just a few shots later, another hydrocharge is fired and we see the same explosion - this is due to footage of one explosion being used twice.