Continuity mistake: When R2 and 3PO are walking in the desert look at the sun's reflection on C-3PO's head throughout the shots. It keeps changing places.
Continuity mistake: Widescreen version: In the trash compactor, in the scene where Han says, "One thing's for sure, we're all going to be a lot thinner," the pole used to stop the compactor is leaning on the wall in different angles between the wide shot and the close-ups.
Continuity mistake: When R2D2 and C3PO escape from the Blockade runner, the rate at which the escape pod turns when seen from the outside does not correspond with what we see from inside.
Other 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.
Factual error: After the Death Star, when TIE fighters are attacking the Millennium Falcon, each time one explodes at high speed, the debris and the fire does not keep moving.
Visible crew/equipment: When Luke and Leia are stuck on the bridge, just before the stormtroopers arrive on the opposite platform Luke remembers the cable and sees the thruster like things over the top of him and Leia, when we get a view of them a small shadow bobs up and down at the centre bottom of the screen.
Continuity mistake: When the Millennium Falcon escapes from the Death Star, each time we see Chewbacca, the sky behind him is dark grey with a few stars rather than black and and full of stars. Some shots later, the sky is normal.
Revealing mistake: In the Death Star, when Chewbacca and Han arrive in the hangar, the shadow of Luke and Leia waiting for their signal is visible.
Revealing mistake: Many times during the film, when someone shoots with a blaster, the shot does not come from the gun. A good example is in the detention block of the Death Star. Luke shoots and the laser comes from 10 centimeters over the gun. Special edition.
Continuity mistake: When the garbage compactor is almost completely closed, Chewie holds the walls with his weapon. In the next shot, he is standing by the wall crying and in the other shot, he is holding the walls again.
Revealing mistake: For this one, you will need a letterbox copy that is not the special edition. In the final award scene, there is a long shot of Luke, Han, and Chewie walking through rows and rows of Rebel Troopers. If you look quickly, the troopers on both ends of the screen are cardboard cutouts. They are cropped off in the Pan and Scan version, and digitised in the special edition, so it has to be the right copy to see this mistake.
Continuity mistake: After Darth Vader kills Obi-Wan Kenobi, Luke shouts "No!" and then there is a gunfight with stormtroopers. During this, R2-D2 is 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's going back into the Falcon for a second time.
Revealing mistake: When the stormtroopers stun Leia, if you watch carefully, you can see that she begins to fall before the beam touches her.
Revealing mistake: When Luke and Leia are trying to pass the pit in the Death Star, Leia shoots at a stormtrooper. The shot passes through him without hurting him.
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.
Continuity mistake: During the conference in the Death Star, the back of Tarkin's chair is higher in the wideshots than in the close-ups.
Continuity mistake: Luke is on the Millennium Falcon practicing with the floating orb. When he is done, he goes to shut off his lightsaber and as it turns off he jumps to the right due to a dodgy edit.
Continuity mistake: When Leia is recording her holo-message to Obi-Wan Kenobi, she pushes a button on R2D2 to finish the message but each time we see the actual message during the film, she turns a huge round button.
Revealing mistake: Special Edition Only: In one of the new Mos Eisley scenes, the speeder goes down a road with two Stormtroopers on each side. The troopers are just mirror images of the ones on the other side of the street. Their movements are exactly the same.
Continuity mistake: When Owen is talking to C3PO, the droid has a wire coming from his head to his back. It's not there in the rest of the film.
Answer: Presumably because the monster has pulled him through the lair of whatever they are standing on into whatever space the rest of the body of the monster lives in. Obviously, the monster doesn't live in the part of the part of the compactor that does the compacting or it would be already compacted.
Myridon