Revealing mistake: The solid brick wall bends like vinyl when Colonel Malloy touches it.
Revealing mistake: In the interior shots of Mobile 1's cockpit, we see that there's a crew of 3 and that the pilot is black. But in shots of the exterior (miniature model stock footage), there's only one occupant, a pilot, and it's a doll with distinctively Caucasian features. (00:26:30)
Kitten Kong - S2-E7
Revealing mistake: When the Goodies are at the park with their animals, Graeme tries to teach his tortoise tricks. When the tortoise jumps, you can see the wire making it 'jump'.
This Male Chauvinist Piggy Went to Market - S3-E1
Revealing mistake: When Laurie goes to flip Goose over her shoulder, it's obvious that a stuntman is actually flipped; he has much shorter hair than the actor portraying Goose. (00:11:45)
Revealing mistake: The councillors put red paint in Beaumont's hat and put it on his head, squirting paint out through the top, but when they are pouring the paint into his hat you can see it already has a hole in it to let the paint out, and the way they are holding the hat shows them covering up the hole to stop the paint coming out before it is put on Beaumont's head.
Firefly, Light My Fire - S1-E1
Revealing mistake: Courage winces and reacts before the stereo-zapper is fired.