When Vader is watching the Emperor attack Luke, his helmet is very dusty and what looks like streaks of finger marks can be seen on the helmet. In the next shot, just before Vader picks up the Emperor, his helmet has been cleaned and is shiny again.
As Boba Fett is aiming at him from behind, Luke can be seen throwing a kick at a henchman (with a "WW2 German style" helmet) that misses by a mile and has no effect. While Boba Fett flies by him after being hit by Han immediately afterwards, Luke throws yet another kick at the same henchman, missing again - yet this time the guy throws away his blaster and jumps overboard.
In Star Wars: Episode V - The Empire Strikes Back (1980), just before Han Solo is encased in carbonite, the metal shackles on his wrists are removed, but the strap binding his upper arms is not removed. When released from the carbonite, his upper arms are no longer bound.
Before Leia is shot, the burn mark is visible on her poncho.
When the Emperor and Vader are trying to make Luke convert to the "Dark Side", Darth Vader's helmet is alternately clean/dusty between shots.
During the speeder bike chase, Luke avoids crashing into two trees that are close together by turning sideways, which would've actually pretty much guaranteed he would crash into them.
When Luke chops Vader's hand off, wires hang out of his arm. The lightsaber would have cut them in line with the rest of the arm.
After the destruction of The Death Star, Endor's forest moon, should have been absolutely devastated going by real-world physics.
When they are approaching the power regulator inside the Death Star , Wedge tells Lando "I'm already on my way out" but he hasn't shot the regulator and hasn't turned around yet - which he does after saying this.
Following the line in Jabba's droid torture chamber, spoken by EV-9D9: "Splendid! We have been without an interpreter since our master got angry with our last protocol droid and disintegrated him," the camera cuts to a 21B Medic droid which is seen being disintegrated. This is not meant to be the actual protocol droid in question, just a demonstration of what happens to droids who displease Jabba.
Endor is repeatedly referred to as the "Forest Moon" or "Sanctuary Moon" throughout the entire movie, yet in the scene when the Rebel Fleet comes out of hyperspace, you see Endor and the Death Star from a distance, but there appears to be no sign of the planet the Endor moon is orbiting. The novelization explains that the planet has been destroyed "of unknown cataclysm and disappeared into unknown realms."
Admiral Ackbar states that the Death Star is "orbiting" the moon of Endor. However, it is actually geostationary above the shield generator. It could be in geosynchronous orbit, which is still an orbit, but with a frequency equal to the orbited body's rotation.
As Ewoks eat humans, as it's almost presented on Han, it's questionable why Leia was safe from this fate after she entered the village. She forged a friendship with Wicket (the Ewok who found her knocked out), so that would have gotten her an "in" with the village. As they have a dress in her size, it's clear the Ewoks have had some positive contact with humans or humanoid species in the past.
When Luke and Leia are having their conversation on Endor, Leia says that she remembers that her mother was beautiful. However, in Episode III: Revenge of the Sith (2005), Padmé dies right after giving birth to Luke and Leia, so Leia couldn't have possibly remembered her.
However the third episode of the 'Obi-wan Kenobi' television series solved it by retconing that memory as a vision through the Force, when Obi-wan talks to Leia while in the back of a truck.
However the third episode of the 'Obi-wan Kenobi' television series solved it by retconing that memory as a vision through the Force, when Obi-wan talks to Leia while in the back of a truck.
When Vader throws his saber at Luke who is hiding on the catwalk in the Death Star, Vader's saber blade is coming out of the butt end of the hilt - not the proper blade end.
Right after Lando says, "Fighters coming in," at the beginning of the space battle, you can literally see TIE fighters in the background appearing out nowhere.
(at around 1h 50 mins) You can see Luke and Vader's shadows, but you can also see the shadows of their lightsaber blades, even though the blades give off light and shouldn't have shadows.
In the speeder-bike chase sequence, several shots are flipped so that Luke's black glove changes repeatedly from his right hand (where it should be) to his left hand.
When the shield generator explodes, a piece of shrapnel can be seen exiting the left side of the screen and then reentering because it bounces of the inside of the building the miniature was housed in.
During the battle over The Sarlaac Pit, when Luke swings his lightsaber at villains and makes contact, it just knocks them over, like he was hitting them with a stick. But given the nature of a lightsaber blade, it should've cut them in half.
At one point when Jabba pulls Leia towards him while she is chained, you can she has a brown birth mark just above her left buttock. Later, when she fires the gun at the sail barge's deck and runs to Luke to swing over to the skiff, you can see the birth mark above her right buttock, indicating one of the scenes was a reverse shot.
When Luke is looking at Vader after his duel in the throne room, his light saber blade is projecting through the top handrail.
The Ewok's captured the gang and were able to tie up Chewbacca to a pole and carry him.
There is a scene where the Ewok's have to swing across a vine to get to the next section. Everyone is being carried on a pole, yet they get them across the swinging vine and then tie them back up on the pole.
When Leia points the cannon at the deck, she runs to Luke who says, "Come on!" but his lips do not move.
When Luke and Leia are on the speeder bikes, Luke says, "You take that one I'll take these two" telling Leia which enemy to attack. When he says this, his lips don't move with the sound at all.
When Han is looking at the Millennium Falcon and wondering if he will ever see it again, Leia says, "Come on, General. Let's move." However, her lips say, "Come on, Cap. Let's move."
When Leia offers Wicket something to eat, as he approaches Leia, you can see her smiling and moving her lips saying something, however, the only thing you hear her say is, "Come on," in a serious tone.
When Han is approaching Endor, he tells Chewie to "fly casual". The words are heard before he starts speaking.
During the speederbike chase, there are several shots where the support arms are visible holding the front of the bikes up.
During the climactic light saber battle, when Darth Vader is searching for Luke in the lower section of the Emperor's throne room, you clearly see that all large structures in the area are suspended from the ceiling with a few support 'poles' holding up the platform that the Emperor's throne sits on. Luke seems to be hiding behind a wall that doesn't exist in the established geography/architecture of the sub-level. When Darth Vader taunts Luke enough to get him to attack, Luke jumps out and the wall is nowhere to be seen as it's just the open staircase behind him.
Boba Fett knows that Darth Vader is hunting for Luke Skywalker, and wants him alive. He would have told Jabba the Hutt about this. It is in their best interest to turn Luke over to Vader for a reward, rather than feeding him to a monster and wasting this opportunity, and possibly incurring Vader's wrath.
After Star Wars: Episode V - The Empire Strikes Back (1980), Darth Vader goes back to build a new Death Star. He seems to forget about Leia and/or Luke instead of setting a trap for them, knowing that they would go to rescue Han Solo. He didn't even bother leaving Troopers nearby just in case. However it should also be noted that the Empire was preparing his final assault against the Rebel Alliance at the time. So they wanted all of their Forces on Endor. And the production of the Second Death Star was very rushed. So, Darth Vader and the Emperor were clearly very busy, and had their hands full.
When Darth Vader died, he should have disappeared like Obi Wan and Yoda did. Since he had been saved and come back to the light side of the force, his fate should have been the same theirs. One could argue that his suit would not disappear with him because it was a part of his evil self and that might be true, but his face can be clearly seen through the flames in the funeral pyre.
When the Emperor first arrives he says to Darth Vader, "in time he will seek you out", Vader doesn't respond. But in the Emperor's throne room he says it again and Darth Vader says, in a surprised tone, "HE will come to ME?"
Lando Calrissian, former owner of the Millennium Falcon, doesn't use the ship's top and bottom gun turrets in the Battle of Endor, for some reason. It is used in deleted scenes that show there was a larger crew on the turrets, it is unknown why they choose to delete them.
After C3PO gives himself up outside the bunker entrance in preparation for the Ewok ambush, the commander shouts "Bring those two down here". Both the current and subsequent shots reveal that he could only possibly have know that C3PO was there as R2D2 was completely out of view to the Imperial forces.
When Leia gets wounded, if you look closely you can spot Han Solo accidentally grab her breast before immediately correcting himself.
During the Battle of Endor, Wedge sends a message to pilots in Red Squadron, yet the pilot who responds to the message is clearly an A-Wing pilot with Green Squadron.
During the Death Star 2 dogfight, a TIE interceptor is destroyed by "Grey Leader" of the Y Wing squadron. However, Wedge ("Red Leader") acknowledges the hit by saying "Good shot, Red 2".
Han thanks Luke for rescuing him, adding that "now I owe you one." Han has already saved Luke twice to Luke's once, so if anything, Luke has paid him back for one and reduced his debt to one.