Continuity mistake: When Memnon is talking to the sorceress in his palace, he talks about the dangers of her being outside "his care." Memnon takes some meat and throws it to the tigers. The next shot shows his hand empty, then holding meat again, and then empty again.
Factual error: All swords in this movie are made from steel, and in the beginning it's said that the film takes place years before the Pyramids were built (they were built around 3200 BC). Steel wouldn't be around for 2000 more years.
Revealing mistake: One of the first times you see Balthazar (Michael Clarke Duncan) you can clearly see the adhesive for the fake scar on his right cheek and that it is coming loose.
Continuity mistake: After the fight scene between Mathyus and Balthazar and the tribe celebrating, you see Arpid arm wrestling a woman. In the first shot he is wrestling with his left arm and in the next shot he is wrestling with his right arm and loses.
Revealing mistake: When Mathayas is chasing the kid who stole his rupees, he crawls into a hole that's just big enough for him to fit through. But when Mathayas crawls in, the hole has grown - he should have only been able to fit on his stomach, but he goes through on his knees.
Continuity mistake: When The Rock first enters the scientist's room, the scientist explains to the child about his magic powder. This is on a device that's slowly turning and sifting off a little of the powder at a time, yet during one cut away and back, a lot more powder seems to have disappeared off the mechanism than it would have pushed off itself.
Factual error: When the guards go into the cave to find Mathayus, and after a guard says "stay on the rocks," a shot shows the feet walking along the rocks. One of the guards is clearly wearing white laces in his shoes. The other is wearing leather laces.
Factual error: During Memnon's training session, at least one of his opponents uses a Japanese training sword known as a shinai. You can see this most clearly after the fight, when one of the weapons lying on the ground comes into view. Not only did the Egyptians and Japanese not have any contact with each other at this time, but this particular training weapon had not yet been invented.
Continuity mistake: In the scene where Cassandra and Mathayus get out of the well after falling through the tub. When they are showing Mathayus from the back of his head his hair looks wet all over but when they show his face, the hair on his head looks dry while the long parts of the hair is still wet. His face has also been dried off when last seen.
Continuity mistake: At the end, when Mathayus is battling Memnon, he is punched and falls off the little ledge they are on. you can clearly see him falling face first, but in the next shot he lands on his right side breaking a table.
Audio problem: When Mathayus and his friends are attacking Memnon's palace, there is a scene where Memnon's general rides at Balthazar on a horse, but then falls off. Balthazar holds a spear at his neck. The shot then changes so we can't see the general and he stabs him and he screams loudly. But if the spear went through his neck (as it should have, as it didn't move anywhere but down) he should not have been able to scream.
Other mistake: When the guards are breaking into Cassandra's bathing room, we see a guard's arm reach through a hole in the door to unlatch it. However, you can see the door has come off the jamb, with a big gap, before he reaches down to pull the latch.
Continuity mistake: When Mathayus is stabbed with the poison arrow, it goes into the side of his right thigh, but when he removes his bandage after Cassandra has healed him, he checks the front of his left thigh just above his kneecap for the injury.
Factual error: The scientist claims that he is working on a magic powder (gunpowder) that was devised by the Chinese. Firstly, the Egyptians had no knowledge of the Chinese in those times and secondly, the Chinese didn't invent the gunpowder for at least another 4,000 years.
Other mistake: In the rebel village toward the end of the movie, Balthzar's scar on the left side of his face keeps changing. Sometimes the scar is barely there and others it is only partially there.
Factual error: In this movie, camels seem to be a common sight in Egypt. However, these animals did not appear in the Nile valley until ca 8-900 BC - more than 2,000 years after this movie takes place.
Continuity mistake: When Balthazar knocks Matathyus down, Matathyus falls face down and his hair gets covered with white bits of dust (sand or whatever). A brief second later, when he stands up, his hair is clean and shinny, but he hasn't had time to clean it, or even made a single move to take the dust away.
Other mistake: In the scene where Mathayus happens upon the hide out of Balthazar and his people and are confronting one another, Balthazar's necklaces change from being messily arranged to neatly graduated in frame to frame. Surely he wouldn't have been rearranging the necklaces while confronting the Arcadian?
Factual error: In the very beginning of the movie, when Mathayus rescues Jesup, he fires several arrows at Jesup's would-be executioners, and the targets of these arrows fly backward, across the room, and smash out the side of the building. I don't think I need to go into a detailed discussion of physics on this.
Continuity mistake: When Mathayus is launched out of the catapult, he is shot out of the window and lands in another room in the castle. A few shots later, the catapult is shown again but it is in the cocked position. The scientist was busy with his gunpowder and avoiding the guards - he wouldn't have re-set it, surely?
Continuity mistake: After Matathyus (The Rock) finishes fighting with Balthazar (Michael Clarke Duncan), Balthazar is sort of sitting down while Matathyus is standing. You see blood all over Balthazar's mouth. Then the shot goes back and forth between Matathyus and Balthazar three times. Each time there's not the same amount of blood in Balthazar's mouth.