When Ki Adi Mundi first draws his lightsaber in the Arena, it is blue. After Yoda and the clones arrive, his lightsaber is green. Seconds later, when he gets on a ship, his lightsaber is blue again.
On the clone ship following Count Dooku, Anakin wants to fire at Count Dooku's speeder, but the ship's command reports that the ship is out of rockets. However, when the camera cuts to Anakin with the wing in the background, four rockets are under the wing.
In the battle arena scene where C-3PO's head is being dragged by R2-D2, C-3PO is heard talking. On Bespin, C-3PO's voice controls were on his back and he was unable to talk until he was joined with his body as this is where power was derived.
When a Clone Trooper finds Padme after she has fallen out of the gunship on Geonosis, she tells him to get a transport ready so they can follow Anakin and Obi-Wan to Dooku's hangar. There's no way she could have know they were going there; she was unconscious when they did.
When Obi-Wan, Anakin and Padmé are chasing after Count Dooku on Geonosis, Dooku's escorts shoot at them. Padmé falls from the ship holding her gun, but in the wide shot, there is no gun to be seen.
A button on a weapon seems to have two entirely different functions.
When Yoda says "Concentrate all your fire on the nearest starship" he doesn't have his signature alien speech impediment. "On the nearest starship all your fire concentrate" would have been more in character. But throughout all of the Star Wars movies, Yoda alternates between his own speech style and more conventional speech; this practice dates back to his first appearance in The Empire Strikes Back.
Obi-Wan and Yoda are both shown blocking Force Lightning. Yet, for some reason, they will never teach Luke how to do so when he is about to face Sidious two decades later, However Luke only trained briefly with Obi-Wan in A New Hope and Luke left is training with Yoda before he could teach him how to block force lightning.
Padmé's decoy, Corde, is seen killed in the beginning when the ship explodes, but in later scenes, we see a decoy that appears to be Corde. This is not a goof, though, as the decoy we are seeing is actually a different decoy, named Dorme (remember, since Padmé's decoys obviously need to be able to impersonate her, they are naturally all going to look similar!), whom we hear her refer to by name (confirming that she IS, in fact, not Corde but a different decoy) just before she and Anakin board the freighter bound for Naboo.
When Padmé is telling Anakin that she wasn't the youngest queen ever elected, she and Anakin are walking on a staircase that leads up to the castle. In the next shot when she is finishing her sentence, she is walking on a bridge. However, this "montage" is an established device in filmmaking to compress scenes.
Anakin's half-brother Owen Lars, who was born since the last movie, appears to be around Anakin's age. However, Anakin only left Tatooine ten years ago. In fact, the movie never actually states Owen is Anakin's half-brother, and only refers to him as his stepbrother. Furthermore, the official Star Wars website states Owen was already a young adult when his father married Shmi Skywalker.
Obi-Wan's beard is noticeably fake in several scenes. This is because actor Ewan McGregor had shaved off his beard after principal photography, and the shooting of additional scenes required a wig and fake beard to re-create his look. Shots include the scene in the elevator to Padmé's apartment, the exchange about the 'changeling' in the Outlander Club and his entire interrogation by Count Dooku.
At several points in the movie, characters are missing reflections and shadows.
When Anakin and Padmé arrive on Geonosis they enter the underground factories. A steel door opens above them and Padmé ducks to enter. However when Anakin follows he does not duck enough and his head passes through the digitally created metal door.
Flipped shot: When Anakin is stalking Zam in the bar, before she attacks Obi-Wan, his plaited hair is on the left side of his head in one shot.
When Obi-Wan is talking to Jango and Boba in their "apartment", Obi-Wan pauses. He's not moving and you can see the back of his head. When Jango walks behind Obi-Wan on the screen, you can see Jango's "shadow" through Obi-Wan.
At one point R2 D2's shadow is facing a different direction to the surrounding tombstones.
When the soldier approaches Padme after she falls off the ship into the sand, she says to gather forces and go the the hangar where Dooku is. She had no way of knowing were Dooku was headed, so she couldn't have known he was in a ship hangar.
After Anakin and Padme first kiss, in the background is a body of water with green mountain behind and a small island in the middle. The shoreline on the far side of the water forms a perfectly straight line. Too straight to be convincingly natural.
In the arena scene when the monsters are approaching, Obi-Wan tells Anakin to "Concentrate". His lips are actually saying the original line, which was "You take the one on the left, I'll take the one on the right". This line was present in the media screenings but changed for the theatrical release.
When Padmé and Anakin are in the field on Naboo talking to one another, Padmé says, "I went into public service," but her lip movement doesn't match what she says.
After Obi Wan sends the message for help to Anakin and Amidala, Amidala says she is going to Geonosis to "help Obi Wan", though her lip movement indicates she is going to "save Obi Wan."
When Padme falls from the ship Dooku shot, she can be heard screaming, but her lips do not move.
Dooku's lightsaber has two different sound effects when he turns it on. The first time, when he is about to duel Obi-Wan, the sound is similar to Luke Skywalker's lightsaber from Star Wars: Episode VI - Return of the Jedi (1983). The second time Dooku turns his lightsaber on, when he is about to fight Yoda, the sound is the same as Darth Vader's from the original trilogy (as well as Darth Maul's from Star Wars: Episode I - The Phantom Menace (1999)).
When Count Dooku addresses the Jedi just before the Clones come to their rescue, the wisps of his hair on the left appear green.
When Count Dooku addresses the Jedi just before the Clones come to their rescue, the wisps of his hair on the left appear green. This is most likely an effect caused by a green screen behind him that wasn't properly edited out.
During the light-saber battle with Anakin, Obi-Wan, and Dooku, Obi-Wan is slashed by Dooku and falls to the floor. Dooku raises his saber to kill him. Anakin dives in and blocks his saber. In the wide shot, not only is Obi-Wan not anywhere to be seen, he almost immediately, THROWS his saber to Anakin. Neither Dooku or Anakin had moved yet. Obi-Wan should have been able to just hand his saber up to Anakin.
When Obi-Wan goes to Yoda's class to discuss about the absence of the planet Kamino he points to a spot and he says the planet should be there as gravity is pulling all the stars in the area to that spot. As a small aquatic planet Kamino's gravity can in no way be noticeable compared to the gravity of a star, even if more than one star is present.
When the gunship is chasing Count Dooku, Anakin orders the gunner to shoot Count Dooku down, to which the gunner replies, "We're out of rockets, sir." Behind Anakin on the wing of the gunship can be seen a full rack of four air-to-air rockets.
During Qui-Gon Jinn's funeral in the previous movie, Yoda and Mace Windu were highly concerned about the remaining Sith. However in this movie, ten years later, the issue is completely forgotten until Dooku mentions the mysterious Darth Sidious to Obi-Wan.
When Jango hands Zane the tube with the creatures inside, he says "they're very poisonous". If something bites to kill, it is venomous, not poisonous. In order for something to be poisonous, it has to be ingested.
Count Dooku (Christopher Lee) mispronounces the name of the Republic Home World. He clearly says: "Coruscanti".
Jedi have signature clothing, instantly recognized throughout the galaxy. However, the drug dealer in the pub picks a Jedi of all people to sell him "death sticks", not even on a remote planet, but on the Republic capitol Coruscant.
When Anakin and Padme travel from Coruscant to Naboo, they are ordered to travel in disguise as refugees. However, Anakin does not hide his distinctive Padawan hairstyle, and Padme continues to dress in her fancy outfits.