Continuity mistake: In the beginning of Luke and Vader's lightsaber duel, and also in a few shots right after Luke knocks Vader down the stairs, Vader's cape alternates between being draped behind and over his left shoulder. (01:48:55)
Revealing mistake: Widescreen version only: After Luke cuts off Vader's hand, the Emperor says, "Now, fulfill your destiny, and take your father's place at my side." In the next shot, Luke's lightsaber blade goes through the railing, without damaging it. (01:49:15)
Revealing mistake: When Han is running from the explosion of the shield generator on Endor, you can see his reflection in the plexiglass that is used to protect the camera from the explosion. Since the reflection isn't of Han's back, the plexiglass must be in front of him. (01:49:55)
Revealing mistake: When the shield generator explodes, a piece of shrapnel flies towards the left side of the screen and then flies back, because it bounces off the inside of the building the miniature was housed in. (01:50:05)
Revealing mistake: When Vader throws the lightsaber at Luke and the platform collapses, the point where the platform's columns connect to the ceiling have expanding circles of smoke coming from them as the columns detach from the ceiling, created by the charges used to sever the platform. (01:50:20)
Other mistake: During the fight between Luke and Darth Vader, when Vader throws his lightsaber at Luke, it is not only Luke's lightsaber from Episodes IV & V instead of his own, it is ignited upside-down, with the blade protruding from the pommel rather than the emitter. (01:50:20)
Continuity mistake: In the first shot of the Emperor's force striking Luke, the Emperor's hands are in a different position from the previous shot. This also happens after he says, "You have paid the price for your lack of vision." (01:50:30 - 01:51:10)
Continuity mistake: In the beginning of the scene where Luke is being electrocuted by the Emperor, the Emperor is standing at the bottom of the stairs. When he says, "Young fool... Only now, at the end, do you understand", he is standing in front of the great window. However, in the next shot of the Emperor, he is standing at the bottom of the stairs again, before he walks down to his previous position. (01:50:50)
Continuity mistake: In the scene of the rebels planting explosives in the bunker, the first shot shows someone with gloves planting an explosive. Then it cuts to a wide shot of Han's team and none of them are wearing that style of glove. (01:51:10)
Continuity mistake: When the Emperor is torturing Luke, in the shot after Luke groans, "Father, please", Vader and the Emperor are standing further away from each other than in the previous and following shots where both are visible. (01:51:20)
Revealing mistake: In the shot where Vader throws the Emperor into the pit, the Emperor is obviously a puppet, because he doesn't move at all. (01:52:15)
Revealing mistake: When Luke and Darth Vader are fighing in the emperor's throne room, they pass in front of a great window. The stars are blurred and they shake. (01:52:30)
Continuity mistake: When Luke pulls Vader away from the edge of the abyss, a wall can be seen behind them, quite close to them. But several times earlier in the movie, there was no such wall in this area of the Emperor's throne room. (01:52:40)
Continuity mistake: During the battle between Luke and Vader, their sabers alternate between casting shadows on the floor, and no shadows. (01:52:40)
Continuity mistake: After Luke cuts off Darth Vader's hand, he turns his head to face the Emperor twice, once in the close-up and once in the wideshot. (01:53:10)
Continuity mistake: When Green Leader's starship crashes into the Star Destroyer, Admiral Piett begins to run away. As the shot ends, he is about one meter away from the window. In the next shot, he is several meters away from it. He couldn't have moved that quickly between shots. (01:54:20)
Continuity mistake: When Anakin Skywalker (Vader) dies, the path of a tear is visible under one of Luke's eyes. Two shots later, the tear path is dry. (01:55:45)
Continuity mistake: When Luke removes Vader's mask, Anakin's eyebrows have been removed in the 2004 DVD. However, a part of his left eyebrow can still be seen in some shots, and it even changes size a few times. (01:55:50)
Suggested correction: It's not part of his eyebrow. It's a shadow.
Revealing mistake: Vader tosses the Emperor and then collapses on some barrels next to the railing. Look at Vader's arm - the one with the severed hand. His arm is bent at the forearm in a way that arms just don't bend. This is because David Prowse's hand was inside an "elongated" arm to simulate it being chopped off. He couldn't keep his wrist straight, giving the appearance of a bent forearm. (01:57:00)
Audio problem: When the Death Star is about to explode, Admiral Ackbar says, "Move the fleet away from the Death Star.", but his lips don't move. (01:57:30)
