Continuity mistake: As Padme and Anakin are about to leave their ship to save Obi-Wan right after landing in the exhaust shaft, she puts on a shawl-like piece of cloth over her shoulders facing forward. When they exit the ship, the shawl is suddenly backwards, with the two ends hanging behind her instead of in front of her. (01:36:20)
Revealing mistake: When Anakin is talking to Palpatine, the shot pans to the door, and it is obvious that the door and the furniture are painted. (00:26:15)
Continuity mistake: In the final shots of R2-D2 and C-3PO after the wedding, the last closeup of the 2 droids shows them with the tree over to the left and you can see clouds, mountains and lake in the gap between the droids and the tree but in the final wide angle shot, the 2 droids are in front of the tree; having jumped to the left.
Continuity mistake: In the scene where Anakin and Amidala arrives at her "home" on a boat we see her stepping onto the edge of the boat as she gets off. Then we cut to a wider shot and we see her stepping onto the edge of the boat again. (00:42:10)
Continuity mistake: At the beginning of the scene where Anakin and Amidala are getting off the transport, R2-D2 is struggling down the stairs some way behind them. Their conversation flows continuously, but as soon as Anakin says "we've got R2 with us", R2-D2 is handily immediately behind them. (00:30:55)
Continuity mistake: In the scenes at the very end when Anakin and Padme are married, the cloud formations in the background against the mountains change significantly between cuts from wide angle to closeups. A little wisp of clouds to the right of the couple disappears and reappears when a closeup of R2D2 and C3PO is shown.
Continuity mistake: In the arena, Anakin asks, "What about Padmé?" and in the background, Padmé has just begun climbing the pillar. Two shots later, we see her reach the top, which means that she has somehow managed to climb to the top of the huge pillar in just two seconds. (00:42:10)
Other mistake: When Obi-Wan goes to the water planet and talks to the Prime Minister in his office. The alien is of course computer generated. When the actors do their blue screen work, markers are put up for them to look at so that when the finished shot is done, and the alien is put in, it looks like they're looking at the alien. In this scene, Obi-Wan is clearly not looking at the alien. (On one of the "making of" trailers at starwars.com you can hear George Lucas jokingly say "Eye-lines! I don't care about no stinking eye-lines," and the scene behind him is Obi-Wan talking to the alien...)
Other mistake: When Anakin & Senator Amidala arrive back on Naboo, shortly after there is an aerial shot of a landing platform of some sort, elaborately surrounded by water and a row of trees. Notice that the reflections in the water do not match the position and height of the trees. (00:38:35)
Continuity mistake: In the scene on Geonosis where the droids are closing in on the remaining Jedi, the camera keeps cutting close and cutting back out. In only two of these changes is a blue Twilek (Aliens with tentacles on their heads like Bib Fortuna) visible. She has disappeared in the other camera angles. (01:56:00)
Factual error: In the introduction, when text flows across the screen, the words "ten thousand solar systems" appear. Strictly speaking, there is only one Solar system - ours. A star with planets is a "star system", our star is called "Sol", hence, the Solar System. This trivial error is made in many sci-fi films, BUT the Star Wars series has never fallen into this error before. Remember Episode IV, where Leia says something like, "The more you tighten your grip, the more star systems will slip through your fingers" (and that's only one example). So why has George Lucas allowed such a trivial but irksome error to be made here? [Some people have debated this point, saying that "Solar" from the Latin "Sol", can mean any star system, but it's backed up in the Isaac Asimov book "Nemesis". He knows a thing or two about sci-fi, and in the book a new star is discovered and called Nemesis, and its system is referred to as the "Nemetic system", as opposed to our own "Solar system".] (00:00:55)
Continuity mistake: As Anakin and Amidala are landing on Tattooine, the sun on the set and the sun reflection off their ship are in different directions. The double sun would not account for this, as they are not far enough apart. (01:03:45)
Audio problem: When the droid army is marching into the arena we see a close up of C-3PO and hear the sound of a marching army but the droids are walking on sand, so the sound should be muffled in some way.
Revealing mistake: When Anakin and Dooku are crossing the hangar shortly after Anakin's green lightsaber was destroyed. Anakin slices a thick cable on the ground causing the lights to flicker. Even at normal speed, it is blatantly obvious he never actually hits the cable, and furthermore the pyrotechnic effect is slightly out of synch with Anakin's motion.