Other mistake: When Larry crosses the street, when going to the museum for the first time, the traffic light for pedestrians is red the entire time. Yet he and other pedestrians casually cross the street (he even stops for a bit) while the yellow cabs don't make any attempt at driving off (although their light should be green). Although there's a small gap between one light turning red and the other turning green, it takes close to 10 seconds while nobody appears to be in any rush.
Continuity mistake: When Rebecca leaves the Museum after sitting in front of the Sacajawea display after Larry asks her to leave as he's closing up, from the internal shot of when she's leaving the Museum she exits through the middle rotating door but on the outside shot she is seen leaving from the door on the right hand side of the Museum.
Factual error: When Larry is running away from Attila the Hun into the elevator, he pushes both hall buttons (up & down). When the elevator is descending, the indicator shows him going down from the top floor. The top floor only has a down button. Also, in that type of Otis elevator, when both buttons are pushed, the up light goes out first, indicating the elevator is answering an up call. The doors would recycle to answer the down direction before the down light would go out.
Continuity mistake: When Nicky turns the stone, there's a close-up shot where a beam of light reflects on his face and he opens his eyes wide. A frame later, from a different angle, the beam is gone and the eyes are shut. Yet when the angle swaps to the previous close-up, the awe expression and light reappear.
Continuity mistake: When Larry "vanishes" the handkerchief and some is left on his thumb, after he says "vanishing" and holds the palms of his hands outward toward the Huns, we see a shot of the Huns, and we see Larry starting to turn his hands back around. However, a second later, when he says "into thin air", he is still holding the palms of his hands outward toward the Huns like before.