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'.
Earthanasia AKA The End of the World Show - S7-E6
Revealing mistake: When Bill says "You certainly know how to hurt a man," and Tim responds by kneeing him in the groin, causing Bill to scream in pain. It's obvious that Tim doesn't actually come close to touching Bill.
Revealing mistake: While the goodies are being chased by the white kitten the wires pulling the kitten along are visible.
South Africa AKA South African Adventure AKA Apartheight - S5-E11
Revealing mistake: When the two guards throw Bill over the gate the dummy doubling for Bill isn't very lifelike.
The Goodies and the Beanstalk - S4-E4
Revealing mistake: While the Goodies are escaping the castle, you can see wires that the birds chasing them are hanging from.
Kung Fu Kapers AKA Ecky-Thump - S5-E7
Revealing mistake: When the pudding flies into Bill's mouth, you can see the wire pulling it.
Kung Fu Kapers AKA Ecky-Thump - S5-E7
Revealing mistake: Bill shoots tea at Tim from two kettles, but if you look at Bill's finger, you can see the trigger for the spray gun shooting the tea.