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)
The Muppet Show (1976)
1 revealing mistake in Mark Hamill - chronological order
Starring: Frank Oz, Jim Henson, Dave Goelz, Richard Hunt
Visible crew/equipment: When the group of pigs, chickens and frogs are singing "Temptation," the head of Dave Goolez (the guy who does Gonzo) is visible under the second chicken on the right several times during the sketch.
Waldorf: These seats are awful.
Statler: Why? Can't you see anything?
Waldorf: That's the problem. I can see everything.