Continuity mistake: After Luke first sees Boba Fett in Cloud City, he begins to walk away from the corner he is hiding behind. In the next shot, he is closer to the corner than in the previous shot. This has nothing to do with camera angles - notice the distance between him and the wall to his left. Also, his right arm is in a different position.
Continuity mistake: When Luke is first attacked by the wampa (ice creature), the amount of blood on him changes between shots.
Revealing mistake: In the first shot of Luke riding on Hoth, the tauntaun leaves no tracks in the snow.
Visible crew/equipment: When Luke and Vader are fighting in the carbon-freezing room, in the wideshot after Luke does a somersault, a crew member is visible in the steam on the right side of Vader, moving out of the way.
Continuity mistake: After Luke places the thermal detonator inside an AT-AT, he falls to the ground. The AT-AT takes only one step before the charge goes off, but when the AT-AT explodes, it is much further away from Luke than one step.
Continuity mistake: In the wideshot where Luke lets himself fall down the pit in Cloud City, Vader lowers his outstretched hand. In the following close-up, he lowers it again.
Continuity mistake: When Janson (Wedge's gunner) fires the harpoon at a leg of an AT-AT, in the first shot of the snowspeeder flying around the AT-AT, the speeder casts a shadow on the snow. In all other shots of this sequence, there is no shadow of the snowspeeder.
Continuity mistake: In an exterior shot in Cloud City, Leia can be seen through the window of a building, with one hand on her hip and the other arm at her side. In the following interior shot, her hands are clasped together.
Audio problem: In the carbon freezing chamber, Han says to Chewbacca, "The Princess - you have to take care of her". When he says, "You have to take care of her", his head is shown from behind, but the motion of his jaw doesn't match the words.
Continuity mistake: When Luke is attacked by the ice creature all the scars are on the right side of his face, but right before he talks to Obi-Wan you see a big scar on the left side of his face, then when he talks to Obi-Wan you can see there are no scars on the left side of his face.
Revealing mistake: In the original (not Special Edition): When the AT-ATs are attacking the Hoth base, they do a camera angle from inside Luke's cockpit. As his snowspeeder is passing through the legs of an AT-AT, part of the cockpit becomes translucent and you can slightly see the AT-AT through a metal bar.
Continuity mistake: In one shot while Luke is being trained on Dagoba, look at R2 when Yoda says, "Anger, fear, agression, the dark side of the force are they." The little projection nozzle that sticks out of R2's head is on the left side of the red light(It's on the right side for the rest of the movie).
Continuity mistake: In the shot before Luke's hand is cut off, his left arm is bent and his elbow is positioned next to a pole. In the next shot, his arm is straight and his elbow is next to a different pole. Also, his lightsabre is held in a different angle. This is best seen in the widescreen version.
Continuity mistake: During the escape from Cloud City, Chewbacca is shooting at the stoormtroopers while R2-D2 tries to open the door. The wall he is hiding behind keeps changing between shots, and the burn mark on the wall also changes a few times, without any laser beams hitting it.
Continuity mistake: Before Han is frozen in carbonite, you can see there is nothing by Leia. When the platform Han is standing on begins to drop, we return to Leia and she now has an Imperial stormtrooper standing by her.
Audio problem: When Lando is punching desperately at the door's control panel in Cloud City, he says "The security code has been changed!" but his mouth doesn't move when he says it.