Continuity mistake: As noted in another mistake, when Han, Leia and Chewbacca are taken captive in Cloud City, two of the stormtroopers change position between shots. This also happens to some of the other troopers, as well as to Lobot, Lando's aide. This is best seen in the widescreen version.
Revealing mistake: If you closely when Vader cuts through the three poles at the end of the lightsaber duel, you can see that the saber never actually goes through the poles. (01:45:50)
Continuity mistake: When the Rebels pick up the signal of the Imperial probe droid, general Rieekan says, "Princess - we have a visitor." In this close-up, his head is straight, but in the next shot, he is standing in a different place, leaning forward. (00:17:35)
Continuity mistake: As Major Derlin and another Rebel officer talk before the shield doors are closed, another officer walks under the starship Leia's standing by. In the next shot, he's gone. (00:11:30)
Continuity mistake: When the Millennium Falcon is pursued by the Star Destroyers after escaping the space slug and, Han pulls the lever for the hyperdrive. In the next shot from behind, the lever has not been pulled.
Continuity mistake: After the Millennium Falcon has left Hoth and Han is trying to repair the hyperdrive, in the shot after he asks for alluvial dampers, the tool box Chewbacca gives him can be seen in the lower left hand corner. When Chewie takes the box, it is lying in a different position than in the previous shot. As Chewie walks over to Han, he is holding the right side of the box with his right hand, but as he puts it down, he is holding the left side of the box with his left hand. There are also more tools in the box than in the previous shot.
Continuity mistake: When Leia briefs a group of Rebel pilots in the hangar on Hoth, the position of her head changes completely between the first and the second shot. As the second shot ends, she begins to turn around, but in the next shot, she has already turned around. Also, Major Derlin's (the man dressed in grey) head has changed position. (00:23:05)
Revealing mistake: During the escape from Cloud City, watch as C-3PO's head strikes a lamp on the hull of the Millennium Falcon. It bends out of shape.
Continuity mistake: When the Empire ship shoots asteroids in the asteroid field, the first one explodes before the laser even hits it.