Revealing mistake: In the scene at the end of the very first battle, where Imperial troops have just taken control of Princess Leia's rebel ship, Darth Vader breaks the neck of the Captain Antilles and tosses his body to the wall. The "dead" Captain puts up both of his hands to avoid slamming his face into the wall. (00:05:40)
Revealing mistake: When the droids head towards Tatooine in their escape pod, a rotating imperial ship is shown in the pod's window, getting smaller as the pod moves away. Regrettably, the star field gets smaller at the same rate as the ship, something that would only happen if you were moving away from a photograph, painting etc. (00:06:55)
Revealing mistake: When Luke and C3PO are outside of the farm searching for R2D2, a droid passes in front of them. You can see lines in the sand, either to keep the robot in a straight line, or where the wheels of the robot have gone in earlier takes. (00:26:50)
Revealing mistake: Sand people are up on a hill overlooking a valley below where Luke is passing by in his speeder. One of the sand people takes aim at Luke, but his companion stops him. Right before the end of the shot, as the speeder is traveling towards the lower right corner of the screen, it becomes transparent. This is a multiple exposure shot, and the path of the speeder wasn't quite lined-up right. (00:27:55)
Revealing mistake: When the Tusken Raiders are seen raiding Luke's speeder, you can actually see the wheels or at least whatever is holding it up off the ground. (00:28:10)
Revealing mistake: When Luke first ignites his lightsaber, he turns it from the right side of the screen to the left side. When the blade is facing the screen, the lightsaber appears flatter than in the previous shot. (00:33:50)
Revealing mistake: When Luke ignites his new lightsaber in Ben's house, the reflection of the stick used during the filming is visible on C-3PO's body. (00:33:55)
Revealing mistake: You can see the arm of the crane used to lower the torture device through the door when it is going into Leia's room. (00:41:15)
Revealing mistake: In the scene where the "torture" robot goes to get information from the princess, if you look carefully on the side of the syringe you will read "monoject", which is an American hypodermic syringe manufacturer. (00:41:30)
Revealing mistake: When C3PO is carrying a dead Jawa to the funeral pyre, it looks like it doesn't have a head, legs and arms. It's like a costume stuffed with a pillow. (00:41:45)
Revealing mistake: If you watch carefully before Han Solo shoots Greedo, you can see that Greedo has been replaced with a faker looking goofy dummy just before he explodes. (00:48:45)
Revealing mistake: When Greedo is threatening Han in the Cantina, there's a black object behind him. When Han shoots him, the object is smaller and some round things appear on the wall. It's visible in the screenshot of the dummy Greedo. (00:50:10)
Revealing mistake: During the escape from Mos Eisley, when Han says, "They're gonna try and cut us off", he grabs the control panel in the cockpit, and the whole panel lifts off the floor. (00:53:55)
Revealing mistake: When an Imperial Officer is running down the tunnel in the Detention Block towards Han, Luke and Chewbacca, Han clearly shoots the top-left hand corner of the tunnel and the Imperial Officer falls down the stairs as if he shot him. (01:14:55)
Suggested correction: This is definitely intentional, not an error. We see stormtroopers being killed by nearby shots throughout the movie, blasters having a smaller 'shock wave' is just a retcon.
Revealing mistake: When they are diving into the trash compactor on the Death Star, one can see the metal bars of the grid, that had previously been cut through, wobble like rubber when one of the team brushes against them. (01:18:20)
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. (01:19:00)
Revealing mistake: After Han Solo runs into the room full of stormtroopers, you can see rubber soles under Chewbacca's feet as he follows him. (01:24:15)
Revealing mistake: During Kenobi's final lightsaber battle with Vader, Kenobi tips his lightsaber downwards, right before a scene change. The white "glow" that should be there isn't, showing the stick-like prop the actors used in filming. There is a small white light at the tip, too. This was not fixed in the Special Edition, but it was finally fixed on the 2004 DVD. (01:31:25)
Revealing mistake: In the Death Star corridor leading to the Millennium Falcon, just before Han says "Didn't we just leave this party?" you can see Carrie Fisher and Mark Hamill's shadows on the wall as they await their cue to run in. (01:31:30)
Revealing mistake: When Darth Vader flies out of the Death Star you see the light falling on the back of the ship change as he clears the bay. Later, when he regains control of his spinning fighter the same shot with the falling shadow is used to show him flying away. (01:49:30)