Revealing mistake: During the lightsaber duel, Vader throws his at Luke. The catwalk behind Luke explodes, but if you watch closely there are two explosions: one some inches over where the lightsaber actually hits and one far on the left.
Revealing mistake: When Luke leaves the Death Star in an Imperial shuttle, a large girder or something falls right in front of his ship. If you watch closely, you can see it bounce, revealing the miniature. A huge, heavy girder wouldn't have bounced like this.
Revealing mistake: During the speeder bike chase scenes, speeders bikes don't affect any vegetation, even though they're flying near the ground at incredible speed.
Revealing mistake: When Leia takes a speeder to chase the stormtrooopers, there is an SFX box around it and it makes no shadow on the ground.
Revealing mistake: When Luke is in the Rancor pit, there is a Rodian in the crowd - some of his fingers are hanging from his hands. Cheap costume. He makes hand gestures like Mr. Burns - helps to find him.
Revealing mistake: After the rebels have destroyed the radar on Endor, there's a shot of Lando and a Sullustean laughing, and after that, a shot of spaceships. One Y-Wing passes in front of an X-Wing, but the light of its engines disappears a little bit before.
Revealing mistake: In one quick scene when Luke's hologram is talking to Jabba, the film has been reversed. The camera shows Jabba sucking on his 'bong' and then pans down to Salacious Crumb. However, during the Jabba shot, the air bubbles in the 'bong' are going down, as opposed to surfacing. Behind Jabba, you can see the smoke created is also going downward.
Revealing mistake: When the Tydirium shuttle is flying toward the Imperial spaceships, there's a frontal shot of it and a strange thing appears near the shuttle for a few frames. It's not the kind of marks that appears on an old film, or a special effects box. It's like a problem with the matte painting.
Revealing mistake: When Luke somersaults over up to a platform above him when fighting Vader, If you look at the hair of Luke jumping, you will notice that the stunt double's hair is much more blonde than Mark Hamill's.
Revealing mistake: When Luke jumps from Jabba's prisoner's skiff over to another skiff, if you watch Lando hanging underneath the prisoner's skiff, you can easily see that he is a matte painting in this shot, because he doesn't move at all (visible on widescreen).
Revealing mistake: In an overhead shot of Darth Vader throwing the Emperor to his death down the Death Star reactor, you can see that it is a dummy in the Emperor's costume and not Ian McDiarmid.
Answer: Yoda. When he was departing for Cloud City to save his friends in the previous film, he promised Yoda that he would return to Dagobah to complete his training.
Phaneron ★
OK. But I thought he was talking about the holeish thing in his hand since he covered it up when he said it. I must have misunderstood it.
The hole in Luke's robotic hand reminds him that he got that robotic hand in the first place because he lost his duel with Darth Vader at Cloud City - a confrontation Yoda warned him he was not ready for.
TonyPH