Continuity mistake: Qui-Gon kicks off Darth Maul with his lightsaber ignited. In the next shot, when he jumps to fight the Sith, the lightsaber is turned off, even though the turning off sound is never heard. (01:55:45)
Continuity mistake: Qui-Gon, Obi-Wan, and Maul are fighting in one of the bridges in the reactor room. In the next shot, when Maul kicks Obi-Wan, the three are now fighting next to a reactor. (01:55:28)
Continuity mistake: When the three Droidekas appear and attack Padmé's group, in the background you can see that Darth Maul has already ignited his lightsaber. After Anakin says "We gotta do something, R2", the Sith ignites his lightsaber again. (01:50:53)
Continuity mistake: When Qui Gon is killed, he falls to the floor with his right arm on the floor. The next shot shows his left arm falling and his right arm on his chest. (01:55:05)
Continuity mistake: At the start of the lightsaber fight in the hanger all three go through some large doors and into the big generator room. Behind them a set of stairs have appeared.
Continuity mistake: When Obi-Wan runs towards Darth Maul and Qui-Gon he is halfway down the walkway, but when it cuts to Darth Maul and Qui-Gon Obi-Wan is now at the far end.
Continuity mistake: When Obi-Wan is hanging from the ledge in the abyss after Darth Maul knocks him into it, he sees Qui-Gon's lightsaber a distance from him and uses the force to grab it. Between shots, the lightsaber changes position on the floor.
Continuity mistake: Sebulba snaps a bit off Anakin's pod and it is left dangling, however in the following scene where Sebulba is talking to Anakin, the part is back in its original position. (00:54:45)
Continuity mistake: When Qui-Gon and Obi-Wan are fighting battle droids in the Trade Federation ship, Nute Gunray says, "I want droidekas up here at once." As he says this, he turns his head, causing the "straps" hanging from each side of his headgear to hang slightly behind his shoulders. In the next shot from behind, they are hanging in front of his shoulders like they normally do. (00:05:55)
Continuity mistake: When the gungan submarine exits the water, you can see water flowing on the force field. The shot later, the submarine is completely dry. (00:21:30)
Continuity mistake: When Darth Maul is fighting with Qui-Gon, only one blade of his lightsaber is on and on the other side there is just a flat end, with no hole. When he fights with Obi-Wan and Qui-Gon in the palace, there is now a hole at both ends. (01:17:25)
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 ★