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.
Revealing mistake: When Jimbo asks the children if they want beer, the campfire stays still for two shots.
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: Mr. Mackey's glasses do not have the part that goes over his nose unless he is looking sideways, then it suddenly appears. (00:17:40)
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.
You Got F*cked in the Ass - S8-E4
Revealing mistake: When the "Asian Kid" is first introduced on the Dance Dance Revolution machine, the arrows are going up the left side (Player 1 side) of the screen, but he is obviously playing on player 2's side. To make matters even worse, the dance pattern on screen doesn't match the way he's dancing, yet the screen also shows that he's doing pretty well.
Fat Butt and Pancake Head - S7-E5
Revealing mistake: At the start, when Kyle gives his presentation, there are 3 duplicates of Milly in the audience: Next to Stan, on the far right next to Clyde and between Timmy and Jimmy in the middle right.
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)
Revealing mistake: When Kenny is at Mick's Lanes, his eyes disappear as he pounds his hands on the table and screams through his parka.
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