Revealing mistake: Before Darth kills Obi-Wan, he rises his saber to prepare to die and his face and hands are perfectly visible. Right before Darth kills him, there's a wide shot where his face is missing and a black object is used to hold the saber, thus revealing the actor was replaced by an empty cloak to achieve the vanishing effect.
Continuity mistake: During the fight against the TIE fighters, the interior shot shows the turrets on the Falcon both point straight up and down respectfully, when in other shots the top turret for example is facing forward.
Suggested correction: There is no objective up or down on a spaceship. The artificial gravity for the turrets are at 90 degree angle to the rest of the ship.
You missed the point of the mistake. Luke and Han are sitting so their backs are parallel to the deck of the Falcon, the guns are then perpendicular to their back, making them perpendicular to the deck of the Falcon. But in exterior shots, the guns are more parallel to the deck than they should be.
Continuity mistake: When Luke is repairing C-3PO at Ben Kenobi's dwelling, he initially has his hands on C-3PO's arm. In the next shot, Luke now has his hand on C-3PO's shoulder.
Continuity mistake: When we see Ben, Luke, R2-D2 and C-3PO on the cliff looking at Mos Eisley Spaceport, you can see Luke's speeder behind the two droids, but when we see a close-up of the four characters, the speeder is nowhere to be seen. (00:42:30)
Continuity mistake: After Luke is attacked by the sand people, a shot shows that his head is laying to the side. In the next shot, its facing straight up.
Deliberate mistake: During the 4 Tie Fighter attack you can see the blue screen octagon matte leftovers surrounding the Tie's trying to blend into space. However it's not the same type of black, so they glow a bit. They are constantly confused as shields, but they aren't. It's real easy to spot if the contrast and lighting on your TV is a bit high, but I spotted it without that.
Continuity mistake: Wide-screen version only: In the trash compactor, after the dianoga has pulled Luke into the water for the second time, Leia is leaning against some garbage. In the next shot, she is leaning forward, the other way.
Continuity mistake: When Obi Wan introduces the lightsaber, he says, "This is the weapon of the Jedi knight." C3PO is disconnected with his head down and in a lighted archway, with some blankets or something by his left side. A frame later, in a close-up, C3PO's head is up, the archway is 'in shadows and the blankets gone.
Continuity mistake: When Ben first gives it to him, Luke's lightsaber is blue, as it was when Anakin dropped it in Episode III. However, when Luke is training against the sphere en route to Alderaan, the lightsaber definitely has a green, not blue, tint to it.
Continuity mistake: When Ben says to Han in the Millennium Falcon, "In my experience there's no such thing as luck", you can see Han is resting his arm on the surface near the control panel, but in the next scene his arm is no longer on the surface.
Revealing mistake: In the scene when Luke, Han, and Chewie are in the Detention level, one of the guards walks toward Chewie. Chewie screams and punches the guard. Look carefully and you'll see the guard starts to jump backward before Chewie's hand comes in contact with his body - in fact Chewie completely misses the guard by about a foot.
Other mistake: When the Falcon is caught in the tractor beam and is being pulled into the Death Star in the next shot after the Death Squad Commander says, "Air bay 327, we are opening the magnetic field," the stars can be seen through the laser guns if you look very closely. This can only be seen in the widescreen version.
Continuity mistake: When Luke Skywalker, Princess Leia, Han Solo, and Chewbacca are in the Death Star trash compactor, Luke, at one point, gets pulled under the water by an alien that lives there. As soon as they leave the trash compactor, however, Luke's hair is completely dry.
Suggested correction: Actually, Luke's hair is still wet; it's just drying.
Continuity mistake: When Luke is climbing to the X-Wing, R2D2 is being brought over right next to where a guy is. He touches the robot and brings it close to him. Shot changes and the robot is away and it's being moved towards the man again. (01:43:46)
Other mistake: In the original release, the lightsabers are not reflected in Darth Vader's helmet or eyes where the other lights in the shot are.
Continuity mistake: When the movie starts, during the shooting C3PO and R2D2 come out from a corridor on the left. R2 is looking to the right. A shot later he is looking to the left.
Continuity mistake: When Alderaan is first seen through the Death Star's viewscreen/window, only half of the planet is lit up. The next time we see it, about 75% of it is lit up. (00:54:45 - 00:55:50)
Continuity mistake: When Leia, Chewie, Luke and Han dive into the garbage chute aboard the Death Star, Han is the last to dive in, about 4 seconds after Luke. Once he hits bottom, it takes Han 14 seconds to get to his feet, orient himself, and fire his blaster. Luke tries to warn Han, but Han fires anyway, and the blaster bolt ricochets around the garbage chute. Luke shouts, "It's magnetically sealed! I already tried that!" But Luke never had time to stand up and fire his blaster before Han arrived. Han was only 4 seconds behind Luke.
Continuity mistake: When Luke and Ben enter the cockpit of the Millennium Falcon during the meteor shower, Ben enters the cockpit twice between shots.
Continuity mistake: When Luke and C-3PO run out of the house to find R2-D2, Luke takes out his binoculars and looks through them. The shot cuts back to Luke and C-3PO, where C-3PO has his arms are by his side, but in the next shot, C-3PO suddenly has his right arm raised almost half way. (00:26:45)
