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: The opening scene was shot twice, complete with a rear-end automobile collision in the foreground for both takes. The initial collision destroyed the taillights of the first car and the headlights of the second car and ruptured the second car's radiator on impact, spilling its contents into the street. The production crew attempted to sweep away the debris with a broom before the scene was reshot. If you examine the roadway before the two cars appear in this scene, you will see a prominent splatter on the pavement that has been swept with a broom almost precisely where the cars impact again moments later.
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.