Other mistake: When R2-D2 cuts the net, only Han, Luke, and Chewbacca fall from it. Maybe C3P0 would have held for a moment because his leg was stuck in the net, but R2 was right over the hole.
Continuity mistake: When Luke takes off Vader's mask, we see Anakin Skywalker with eyebrows on him, but in Revenge of the Sith, Anakin burns on Mustafar and his hair and eyebrows are gone. This has been fixed on the 2004 release.
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.
Audio problem: When the shuttle Tydirium is approaching Endor, look closely when Han says, "Fly casual" - he begins to say the words before his lips start moving. When he stops talking, his mouth is still moving.
Continuity mistake: In the scenes where the Emperor is trying to convert Luke, watch the stars through the window behind him. The same group of stars go floating past every time.
Continuity mistake: Look at the full body shot of the holographic Luke. Luke, who normally has his lightsaber clipped to his left hip, now has it hung from his right hip. As well, his hair, which normally has a part on his left hand side, is now parted on the right. Afterwards, just before Artoo turns the message off, we get a shot from behind Artoo, and Luke's hologram is visible on the extreme right of the screen. Luke's lightsaber is now hanging from his left hip where it normally is.
Audio problem: In the desert after Luke starts putting his rescue plan into action, Han says "Boba Fett", before hitting him unintentionally. He immediately says "Boba Fett" again. It is the same sound, looped.
Other mistake: On Endor, after Han Solo's group was captured, C-3PO called out to the Empire's soldiers. One of them said "Bring those two down here!" Both C-3PO and R2-D2 were up there, but from the Imperials were standing, they could only see C-3PO. R2 was hidden behind a tree. They wouldn't know that he was there until they actually got close to the two.
Continuity mistake: When Han is speaking to Lando before he departs for Endor, the distance between the two men changes between shots.
Continuity mistake: Before the rebels take off for Endor, Han says to Lando to take the Millennium Falcon as "she's the fastest ship in the fleet". At this point, Lando can be seen moving his head down, but as the scene changes he is looking straight ahead again.
Visible crew/equipment: During Luke's conversation with Ben's ghost, you can see a boom microphone in the background. This applies to the original wide-screen version.
Continuity mistake: Outside the bunker the position of the bodies keep changing or moving throughout the battle on Endor.
Continuity mistake: When R2-D2 is shot by an Imperial stormtrooper whilst trying to open the shield generator's doors, he goes into the side wall and you can see a door open on his body with an interface arm sticking out of it. But when Han shoots the stormtrooper dead, we cut back to R2, and the door that was originally open is now closed.
Continuity mistake: When the Rebel fleet is preparing to make the jump to hyperspace to the second Death Star, the small fighters move first. Then the big ships. But when the big ships move into hyperspace, there are only the Medical Frigate, some transports and some Blockade Runners. What happened with the big Correllian command ships?
Answer: The Jedi are shown to have something of a blind spot in regards to matters of the heart. Note that when Luke confronts Obi-Wan over lying to him about his father's fate, Obi-Wan's response is haughty and defensive, and gives Luke nothing in terms of regret or apology. They're focused on their mission, not on how Luke feels. Why waste time, in their eyes, telling Luke about his mother? If they had their way, he wouldn't even know about his father. The prequels would make this more explicit, showing that the Jedi are conditioned from the beginning to let go of all "passions" because they could so easily be corrupted, and their inability to understand Anakin's emotions just contributes to his downfall.
TonyPH