Butters' Very Own Episode - S5-E14
Continuity mistake: Butters' mom is holding a knife, pointed at her shoulder, but in the very next shot it is down near the cucumber, and then goes back.
Butters' Very Own Episode - S5-E14
Other mistake: When Butters is travelling down the river in his mom's car, the passenger door opens just before the car hits the rock.
Butters' Very Own Episode - S5-E14
Continuity mistake: When Butters' mom paints his face with the roller, the paint is the color of the wall rather than the color she is painting. (00:05:00)
Butters' Very Own Episode - S5-E14
Continuity mistake: When we view Butters from the front of the car, the clip of his seatbelt is above the seat, but when the shot changes to a closeup of Butters, the clip is below the top of the seat. (00:07:55)
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