The Movie Mistakes blog

When the stormtroopers break into the control room, the stormtrooper on the right of the screen hits his head on the door frame. On the DVD release they've added a thump when he hits it.

When Darth Vader and Ben are fighting, Darth's chestplate is on backwards.

When Luke is in Obi-Wan's house trying Anakin's lightsaber, the coat behind him keeps appearing and disappearing.

In the first shot of the Millennium Falcon, the ship is missing its radar dish.

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.

The ammo belt of Chewbacca appears on him just before the jump into hyperspace.

When Luke and Obi Wan arrive at the Cantina, watch the Jawas sitting outside the Cantina. They're initially sitting in a shadow, but when Luke and Obi-Wan walk towards them, they're suddenly in broad daylight.

When Luke uses the comlink to call up C-3PO to ask how to get out of the detention block, a rack with 3 blasters can be seen in the control room. But right before the stormtroopers enter the control room, there are suddenly 4.

During the conference in the Death Star, the back of Tarkin's chair is higher in the wideshots than in the close-ups.

When the Tuskan Raiders are seen raiding Luke's speeder, you can actually see the wheels or at least whatever is holding it up off the ground.