Factual error: The city at the beginning of the film where the Pharaoh lives is named as Thebes, and you can see the Sphinx and the pyramids in the background, but these are in Giza, not Luxor, as Thebes is now called. (00:00:30)
Revealing mistake: At the very start, as Anck Su Namun walks towards the camera, you can see two circular plasters underneath her body paint, preventing her from becoming too exposed. (00:01:20)
Continuity mistake: The pharaoh realises that his mistress Anck Su Namun was touched by another man because the body paint on her left shoulder is smudged. However, the way it is messed up differs drastically between when it was being smudged by Imhotep and when the pharaoh points to it. (00:02:40)
Continuity mistake: When they show Anck Su Namun committing suicide at the beginning, when the Pharaoh's guards show up she whips around to face them and all of her hair goes over her left shoulder. None is left on her right shoulder. However, in the shot from the front, she has half of her hair over each shoulder. (00:03:20)
Factual error: I counted five canopic jars, one of which has the head of a lion. In ancient Egypt there were only four canopic jars - Hapi, the baboon-headed god representing north, Imseti, the human-headed god representing south, Duamutef, the jackal-headed god representing east and Qebehsenuef, the falcon-headed god representing west. None have lion heads. (00:04:20)
Continuity mistake: This is in the beginning as Rick and his men are crouched behind a wall, facing an on-coming army. The soldier to Rick's left is positioned approximately half a head higher than Rick. In a subsequent shot, their heads are now on the same level. (00:08:15)
Visible crew/equipment: In the opening action scene, when the raiders start firing their guns towards the French Foreign Legion, there's a wide-shot of several French troops being killed, and a few of them fall over a balcony to their death. As some of the soldiers on the left side of screen fall of screen and land behind some piles of sand, you can briefly see the edge of an air bag (or some other form of padding) pop up a few times with each one. (00:09:06)
Other mistake: During the opening action scene, as Rick is firing the pistols after he backs up from the outer wall (shortly before he finds Beni and is locked outside the tomb), pay attention... you can see that many of the extras in the background aren't really doing much of anything even though the two groups are supposedly in battle. A lot of the raiders and doreign legion members are just standing around or aimlessly walking. Only a few of them are (poorly) pretending to "fight." (00:09:50)
Continuity mistake: When O'Connell is locked out by Beni his .45's are empty and the slides are locked open on both. When he throws his pistols ahead and does a dive/somersault move, then goes for one of his pistols, the slide has closed. (00:10:10)
Factual error: When Rick is running from the horsemen at the begining, he stops in front of a pillar and waits to be shot. We see the horses round the corner and rear back in fear and one falls over. We then see Rick again and then cut back to the horses, which have all disappeared. There's no way a horse could get up and run off that fast with a rider. (00:10:55)
Continuity mistake: In the scene in the library, when Evie is putting back the books. She leans over to put the book back, but it falls to the ground and she is balancing on the ladder. When the camera cuts back to show the whole ladder, the book is nowhere to be found on the floor. (00:13:00)
Continuity mistake: At the beginning of the movie when Evie is putting the books back, she is standing on the ladder leaning against the bookshelf and the top rung of the ladder is at mid thigh. When she reaches and the ladder stands up the top rung is at breast level. (00:13:00)
Other mistake: When Evie is in the library and all the book cases start to tumble over, if you look at one of the corner book cases you can see a piece of paper landing on it and the books are clearly painted on a flat piece of cardboard. (00:13:30)
Continuity mistake: In the scene where Evie & her brother meet Brendan's character for the first time, the guards bring Brendan out with both arms shackled together in front. After he kisses Evie the guards pull him away and one of his hands is suddenly free - he quickly tucks it behind his back as he's dragged off. (00:19:35 - 00:21:15)
Audio problem: When Jonathan and Evelin are about to board the boat after Rick gets on, Jonathan says "Yes, yes, you're right. Filthy, rude and a complete scoundrel, there's nothing to like there at all." Before he finishes his sentence it cuts back to Evelin, and his lips don't move. (00:23:30)
Visible crew/equipment: During the fire/gunfight on the boat, you can see earplugs being used by the Americans while they are firing their weapons. (00:32:00)
Continuity mistake: When Rick is fighting Benny on the camel when they are riding towards the temple Rick and everything else is in shadow in some shots even though the sun is high up and there are no clouds. (00:38:30)
Continuity mistake: When the two teams are racing towards the city of the dead on horses and camels you can see that Evy's knees are exposed as she passes Rick, yet in the next shot they are completely covered by her dress. (00:38:55)
Continuity mistake: In the scene where Evie, Jonathan, Rick and the fat guy drop down into the mummy preparation room, you see the fat guy pick up his tools and start walking forward, then in the next scene, you see the exact same thing. (00:41:15)
Continuity mistake: When the party of Rick, Evy, Johnathan and the Warden go down into the burial chamber for the first time, the warden bends down to grab his stuff. Then it zooms in on the other three, but you see in the background the warden once again bending down. (00:42:15)
Suggested correction: Why does it matter. They added a fifth. No reason after making up a lot of history and a cover to cover book instead of a scroll for us to suddenly go, hmm, they gave the ten plagues of God in the Bible to an Egyptian priest? Lions are cats. Therefore worship, plus the lioness goddess who slew through the land once. They can certainly add that and might make it a nicer play on the mummy's power and deadliness comparatively to the canopic heads and their gods.
A better excuse is the fact that the earliest found canopic jars are from the 11th dynasty (2200 BC) whilst the jars in the movie are way older than that (2700 BC) and could have represented anything they wanted and be more than 4. Someone should make a correction like that.
lionhead
There is no real excuse. It is simply an inaccuracy and the trivia section to include it as such. It certainly "does matter".