Revealing mistake: When Leo Sayer is in the tree singing you can the wire on his back supporting him.
The Muppet Show (1976)
1 revealing mistake in season 3
Starring: Frank Oz, Jim Henson, Dave Goelz, Richard Hunt
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)
Waldorf: Well, you gotta give them credit.
Statler: Why's that?
Waldorf: Well, they're gonna keep on doing it till they get it right.