Revealing mistake: In the shot where Han Solo and Luke jump down the garbage chute, Smoke outlines the end of the corridor, revealing it is a board with the scenery on it.
Continuity mistake: After the droids leave the control room of the Death Star, there's a close-up of Luke in the trash compactor, pushing against some garbage. In the next shot, he is pushing against the wall.
Continuity mistake: When Han and Leia try to use a pole to stop the trash compactor, Leia says, "Help me." Two shots later, Han can be seen lifting the pole. In the next shot, Leia is suddenly lifting it with him, and Han is holding the pole differently.
Continuity mistake: Special Edition: When Han is talking to Jabba the Hutt, when Jabba begins to says, "What if everyone who smuggled for me dropped their cargo at the first sign of an Imperial starship?", Chewbacca can be seen walking behind them. In the next shot, he is suddenly walking next to a wall that was nowhere near him in the previous shot. In the following shot, he is back to his original position.
Continuity mistake: When a confrontional alien thug threatens Luke and Ben interferes, the thug has his hand on Luke's upper arm. In the next shot, his hand is on Luke's shoulder.
Other mistake: In the trash compactor, after C-3PO realises that he turned off the comlink, Leia grabs the bar used to stop the compactor and her hand sinks in and puts a dent in the bar. When she loosens her grip, it returns to normal. No wonder it was useless at bracing the walls...
Continuity mistake: After Darth Vader kills Obi-Van Kenobi, Luke shouts "No!" and then there is a gunfight with stormtroopers. During this, R2-D2 is seen going up the ramp into the Millennium Falcon. But a few shots later, when Han Solo says "Come on!", you can see R2-D2 at the bottom of the ramp and he going back into the Falcon for a second time.
Continuity mistake: After Owen buys C-3PO from the Jawas, Luke says, "All Right. Come on." and R2-D2 begins to turn his head/dome. In the next shot, his head is still turning, but his dome is in a different position from the previous shot, evident from the droid's features.
Continuity mistake: In the trash compactor, Han says, "One thing's for sure, we're all going to be a lot thinner." In the next shot, Han and Leia are both standing in a totally different position. For example, both of them are looking in another direction, and Han's left hand is in a different position.
Continuity mistake: As R2-D2 is rolling through the canyon, he's on a smooth part of the land. He then stops and looks around. When he starts moving again, the terrain has changed and is now full of rocks and pebbles.
Deliberate mistake: Just after Obi Wan kills the two aliens in the Cantina, there are two quick "reaction shots" from both ends of the bar. If you are quick, you can see that they are both shots of the same end of the bar with one shot flipped. You can see the same human with the light blue/dark blue suit on in both shots.
Continuity mistake: In the scene where Luke finds the remains of his aunt and uncle, in the shots from behind Luke, the wind is blowing from his left. In the shots facing him, the wind is blowing from his right.
Other mistake: During the chasm crossfire scene, Leia says, "Here they come" and points the blaster upwards as she aims at the stormtroopers above. But the laser moves downwards.