Mark Hamill - S4-E16
Revealing mistake: When Luke Skywalker is introducing his 'cousin' Mark Hamill at the end, you can tell it's a split screen by the fact that Luke looks right past him, even once he's on stage. (00:25:10)
Revealing mistake: During the opening credits, after Merlin appears, we see Shaggy for about 1-2 seconds with no arms.
Cruise (1) - S3-E6
Revealing mistake: In the beginning of the show, Shirley is ironing Laverne's clothes and leaves the room. The iron falls on Laverne's clothes on the "L" and burns it, When she picks up the iron, the "L" is on the bottom of the iron facing the normal way when, in fact, it should have been a reverse image.