Pilot: The Spirit of Christmas (Jesus vs. Santa) - S1-E1
Revealing mistake: Each time Jesus turns his head to speak to the children when he is beating Santa Claus, he has two left arms.
Cartman Gets an Anal Probe - S1-E2
Revealing mistake: When Cartman finishes talking about his nightmare in the beginning, Chef comes and you can see his hat poking out of the roof of the car. They couldn't really fix this because this episode was done out of construction paper. (00:04:10)
Revealing mistake: When Jimbo asks the children if they want beer, the campfire stays still for two shots.
Revealing mistake: Right after Wendy tries to convince the crowd that Cartman's actual paper was 'Walden' with Cartman's name on it, Stan mentions something about Kyle's mom making tuna fish sandwiches. When he does this, you can kind of see him 'lift' off the background.
Revealing mistake: When Cartman walks in on Sally Struthers eating the cake, the cake has holes in it, and part of her hair goes in front, and part of it is visible through the cake. All of the other slices have holes in the same place as well.
Cartman Gets an Anal Probe - S1-E2
Revealing mistake: When Stan walks away from Kyle while saying, "I gotta get a piece of loving while the getting's hot," a blue piece of construction paper briefly appears at the bottom right for a second. At the same time, what appears to be a big and a small shadow briefly appear at the top right for a few frames. Then, after Kyle says, "Rats," a human hand suddenly appears on screen for one frame. (00:13:08)
Cartman Gets an Anal Probe - S1-E2
Revealing mistake: When Chef is waiting for the visitors, he lifts his sunglasses. When he does, he blinks. But his eyes appear over the sunglasses. (00:19:25)
Answer: He appears in at least 5 other episodes, but usually just as a background character. He can be seen at Cartman's party in "Immaginationland". He was also one of the kids trying out to replace Butters in the "Professor Chaos" episode.
Bishop73