Continuity mistake: In the scenes in the conference room in the Death Star, the black hemisphere on the conference table changes position between shots.
Continuity mistake: During the binary sunset, the two suns are closer together in the close-up than in the wide shot. There is also a cloud and a mountain in front of the lower of the suns, which weren't there in the wide shot.
Continuity mistake: When the Jawas arrive to sell the droids, Luke walks over to R5-D4 (the "R2 unit with a bad motivator"), and the droid is standing in front of R2-D2 on Artoo's left. In the next shot, the two droids are standing perfectly next to each other, and there are several Jawas around them that weren't there in the previous shot.
Continuity mistake: The first time Chewie gets into the cockpit of the Millennium Falcon, he hits his head on a small set of dice. They aren't seen in subsequent shots, nor are they seen in the rest of the trilogy.
Continuity mistake: In the Detention Block, Han and Luke are in their stormtrooper outfits and are firing at the enemy. They go to a shot of Han then to Luke. Luke's white shoulder pads of his stormtrooper outfit are clearly missing, and you can see a black undergarment. They then go back to Han and then back to Luke again, where the shoulder pads are now back. (01:15:20)
Continuity mistake: In the scene where stormtroopers are firing at the Millennium Falcon as it leaves Mos Eisley Spaceport, watch the trooper on the far left. After he is shot he begins to fall, then suddenly he's standing again in the next shot, where he begins his fall again. This happens two or three more times, this falling and straightening.
Continuity mistake: In the end scene, when they blow up the Death Star, whether the camera is on the Ties or X-wings, the enemy is never visible in front or behind them.
Continuity mistake: In the wide screen version, after Luke, Han, Chewy, Obi-Wan and the droids come out of the hidden cargo bins in the Falcon, Obi-Wan says "Who's the more foolish, the fool or the fool that follows him." Then he tries to lift himself out of the bin...it looks as if he doesn't quite have the strength to do it - he puts his arms on the side, exerts a bit of pressure, and waits for the cut.
Continuity mistake: In the scene where R2-D2 is rolling down a path on Tatooine, under the eyes of scavenging Jawas, the path he is traveling on can be seen to end several feet in front of R2, and beyond it is a rough, rocky surface that R2-D2's wheels could not possibly traverse. In the next shot, R2 is rolling down a suddenly extended (or perhaps the same?) path towards capture.
Continuity mistake: When you first see the Millennium Falcon, it is in the hangar. If you look close enough, you can see that only half of the ship is there. This is because it was too expensive to build a full-scale model.
Continuity mistake: When Han Solo and Luke Skywalker escort Chewbacca up to the Cell Bay to rescue Leia they are still wearing the stolen Stormtrooper uniforms, including white boots. Yet after they escape the trash compactor they are back in the boots they were wearing when they escaped Tatooine. While we can believe the rest of their outfit can fit under a Stormtrooper uniform, the boots wouldn't.
Continuity mistake: When Vader picks up the rebel in a choke grip, the legs of the stormtrooper in the doorway behind them are apart. In the shot of the rebel's feet, the trooper's legs are together. When Vader tosses the dead rebel into the wall, the trooper's legs are apart again.