Continuity mistake: On the DVD version of the movie there are some deleted scenes - one would have explained two mistakes that occurred towards the end of the movie. Mistake one was that there was a hole in the ground when Jonathan and Rick are at the base of the statue of Horus. You can see the hole clearly when Rick lights the TNT - but without the missing scene there is absolutely no reason for that hole to be there and it just sort of appears. (01:42:30)
Continuity mistake: When Rick stabs Imhotep, at the end of the movie, we can see blood on the hands of the mummy. In the next shot, however, his hands are clean and there's no blood coming off the wound. (01:51:00)
Continuity mistake: Just out of curiosity, where did the bandage come from on Fraser's hand at the end of the movie? [He got burned by the salt acid in the deleted scene. An explanation, but given the editing, still a valid mistake.] (01:55:25)
Factual error: In the gunfight on the Nile-boat, you can often see (and hear) Rick fire his revolvers 20-24 times in totum without reloading. The guns he has would only take 6 rounds per gun (MAS 1873 revolvers).
Factual error: Due to the Earth's rotation, the mirror system used to light the tombs would only provide light for about 4 minutes before needing readjustment (tested by the Mythbusters). This would be fine when there were plenty of priests around to adjust them constantly but the light level never changes even though we see Rick and Evie for several minutes at a time.
Continuity mistake: Ardeth Bay removes the Lewis gun from Winston's plane after it crashes in the desert. If you look at the gun, it has the correct 97 round drum (it's really noticeably thick) with a leather carrying handle on top and no paint marks on it - this is correct for aircraft use. Aside from the fact we never see Ardeth Bay remove any spare magazines for it (which would also have been of the 97 round variety), which would have left the gun with little if any ammunition after shooting at the wall of sand, by the time they all arrive in the treasure room, the magazine suddenly changes to the 47 round variety (thinner than the 97 round magazine), which does not have the leather carrying handle, and has the painted marking on the top of it to enable the magazine to be more easily changed at night.
Continuity mistake: When Evie wakes up with the rat on her, she rolls over and sees Anck-Su-Namun's body and screams. A split second before the camera cuts, you can see a large crack form in the top-left corner of the table Anck is on. The next time you see the table, the crack is gone. Clearly, it was unintentional damage done to the set that was later fixed. (This mistake has been fixed in the 4K version, which seems to have the crack painted out, but it's still visible in older DVD/Blu-Ray versions).
Continuity mistake: In the scene where Imhotep's sarcophagus is opened: Rick and Jonathan stand the sarcophagus up against the wall, and Evie steps a few paces away and stands in front of it. Then the "lid" falls on the floor, where Evie was standing. Then Evie approaches the juicy corpse of Imhotep from an angle. Next she is seen stood directly in front of him, where the lid should be, yet the lid has mysteriously disappeared.
Continuity mistake: When Imhotep's priests break out of the ground, we see a shot of Ardeth, Jonathan and O'Connell starting to shoot them. It flashes back to the priests and then back to the trio and we only THEN see Jonathan reach over and grab some revolvers from beside O'Connell to start shooting.
Continuity mistake: When the biplane dives from the sandstorm created by the mummy, it shows Evelyn looking towards the plane, with the city of the dead behind her. The plane is seen, from her viewpoint, to be flying away when it crashes. However, after the plane sinks O'Connell and his friends walk in the same direction that the plane was flying, presumably AWAY from the city of the dead but the camera shows them walking towards it.
Continuity mistake: During the scenes when Rick, Evelyn, and Jonathan are walking through the passageways by torchlight, Rick's leather wrist bracer disappears and reappears.
Deliberate mistake: The shot of Ardeth and his companions watching Rick leave Hamunuptra at the start of the film is reused again when Rick, Evie, Jonathan and the Warden re-enter Hamunuptra, although the reused shot has a blue filter over it. Ardeth even says exactly the same line he says in the original shot, but it is subtitled differently.
Deliberate mistake: When they first enter the tomb, Evie moves a mirror which deflects light onto a load of other mirrors. You can see the beam bounce from mirror to mirror as it goes along the chain. Whilst this looks cool, the speed of light is far too quick for this to actually be noticeable as shown.
Continuity mistake: After the scarab enters his body, Jonathan contorts his arm in pain/reaction giving a view of his palm, through which the scarab entered. But there is no visible wound, blood, or any other sign of entry for the scarab to have gotten in. Also there is no visible blood when Rick stabs Jonathan to get the scarab out.
Continuity mistake: On the boat, as Rick is checking his weaponry, he cocks his 45 and puts a magazine in. Hearing a noise, he walks over to deck cargo and pulls Benny out. He then places the 45 against Benny's chest and threatens him. The 45 is no longer cocked.
Factual error: The head of the prison is described as the "warden". This is an American term. In countries dominated by Britain, as Egypt was at the time, the head of a prison is the "governor".
Continuity mistake: In the beginning, during the initial battle sequence, there is a scene where some men on horses go up a little hill, over all these dead bodies. The body right in the middle of the shot jumps two different times when a horse runs over his legs.
Visible crew/equipment: In the shot where our heroes are climbing down into the tomb for the first time you can see Brendan Fraser holding the handle of a wire which was removed digitally. This is even mentioned in the director's commentary on the DVD.
Revealing mistake: In the initial battle sequence, in one shot you can see the special effects canister from which the sand explodes up.
Continuity mistake: When the hero and heroine are kissing, you first see it from behind him looking at her face. From that viewing angle they both turn their heads to the right to kiss each other. Then we see it from behind her and in front of him, but now they are both turning they heads a little to the left.
Answer: Beni: As long as I serve him, I am immune. Rick: Immune from what? Beni: Piszkos állat [this is Hungarian for "filthy animal," an insult directed at Rick]. Rick: What did you say? Beni: I don't want to tell you. You'll just hurt me some more.
Charles Austin Miller