Continuity mistake: When the queen's ship lands on Tatooine you can see that there aren't very many big rocks near the ship but later when Panaka and Obi-Wan are talking about the storm they pass a row of rocks that wasn't there before.
Continuity mistake: Before the pod race begins, as Jabba the Hutt says, "Welcome.", the woman to his right has her hand on the wall. In the next shot, she is no longer touching the wall and her head is turned in a different direction. (01:56:00)
Continuity mistake: During dinner, as Anakin says, "I had a dream I was a Jedi", his arms are on the table. In the next shot, they're off the table, and there's a piece of cutlery in his food bowl, which wasn't there in the previous shot. (00:40:25)
Continuity mistake: During the battle in the hangar, the Droidikas roll out and stop near the ship exit, but when the Jedis ignite their lightsabers, we see the droids are missing in the background.
Continuity mistake: When Jar Jar goes to retrieve the wrench that he dropped in the engine of Anakin's podracer, he moves his hand towards the upper part of the engine. In the next shot, he sticks his hand into the middle of the engine. In the following shots, his hand remains in the middle, but when he says that he's stuck, his hand is once again in the upper part. (00:46:45)
Continuity mistake: Right after Anakin blows up the generators on the droid control ship and he is flying out of the hanger you can see a close up of R2, his lens is on the wrong side.
Continuity mistake: When C-3PO meets R2-D2 for the first time, Natalie Portman and Jake Lloyd (Padme and Anakin) can be seen in the background. They are obviously NOT watching the action in the foreground, but instead Mike Lynch, the robotics operator, moving 3PO about.
Continuity mistake: When Anakin is sitting in his Naboo starfighter about to take off, there is one shot of R2 with his projection nozzle on the left side of the red light instead of the right.
Continuity mistake: When Qui-Gon first talks to Watto about the pod race, Watto's arms change position during the first three shots. (00:42:50)
Continuity mistake: When Qui-Gon delivers the hyperdrive, the way he holds the reins of the eopie he's riding changes between the first two shots. (01:08:25)
Continuity mistake: When Anakin and Padmé arrive at the Podracer hangar, Anakin is taller in the first shots than in the shot where he gets off the animal they're riding on. (00:51:45)
Continuity mistake: When Amidala's starship runs the blockade, after the spacecraft flies towards the screen, there's a shot where R2-D2 is missing from the top of the ship. (00:25:35)
Continuity mistake: As someone else has noted, Obi-Wan's braid changes sides a few times in the movie. In the first scene with Jar Jar, his braid stays on the correct side of his head, but after he says, "If they find us, they will crush us" it goes from hanging in front of his shoulder to hanging behind it. (00:12:05)
Continuity mistake: When Padmé is to come with Qui-Gon after the Queen's ship has landed on Tatooine, he says, "This is not a good idea", and something blurry flies by in the upper right hand corner. It is not there before or after. (00:29:25)
Continuity mistake: Jar Jar knocks down a bunch of droids in Watto's shop, but when they leave, you can see the feet of the now stacked up droids. (00:33:15)
Continuity mistake: When the final duel between Obi-Wan and Darth Maul begins, they are fighting in a particular area next to the pit. But when Obi-Wan cuts Maul's lightsaber in half, the background changes and they are suddenly fighting on a different side of the pit. (01:56:40)
Continuity mistake: During the funeral pyre scene, the folds in Obi-Wan's hood change between consecutive shots.
Continuity mistake: When Palpatine and Queen Amidala address the Senate, the holocam flying around near them is inconsistently placed between shots.
Continuity mistake: In the first scene in Watto's shop, a cloth lying on a device on his desk keeps changing position between shots. (00:30:25)
Continuity mistake: When R2-D2 and three other astromech droids fixing the Nubeing ship, Jar-Jar is talking to them and there is a black one. This black one turns into a blue one when they are fixing the ship. It's the second one to get blasted.
Chosen answer: According to "Inside the Worlds of Star Wars: Episode I" by Kristin Lund, they are "laser doors which lock into position in response to potentially lethal power outputs that occur intermittently during plasma activation process" (the fight takes place in a plasma energy processing plant). There are six laser doors in deference to an ancient Naboo legend in which Chaos is held back by six inpentrable gates. As you say though, they're really just a plot device to add dramatic tension to the duel!
Sierra1 ★