Plot hole: Christopher Columbus speaks Italian while the Huns supposedly speak their native language. Shouldn't Octavius and his Romans speak Latin? (00:34:50)
Continuity mistake: When Larry does the magic trick with the disappearing handkerchief, the amount of coloured handkerchief visible out of his thumb changes massively between shots. (00:59:00)
Continuity mistake: When the T-Rex is going after Larry, Larry is behind a desk. The T-Rex bangs his head on the desk and then lifts the desk and throws the desk. A few scenes later the desk is back in place and there is no mess from the papers that were there before. (00:22:50 - 00:23:40)
Continuity mistake: Sacajawea is pushed down by Teddy and falls face-up, but lands face-down a shot later. Though she could've turned around while falling, she only has half a second while freefalling in panic, so it's quite impossible for her to turn around.
Continuity mistake: When Larry first meets the Easter Island head, he is talking to him from about 5 feet (or more) away. When it cuts back to him after the shot of the people chasing him, he is just inches away from it. (00:24:50)
Continuity mistake: When Larry notices the caveman's footprints leading to the open window and goes to investigate, the footprints are gone in the next shot. (01:05:25)
Plot hole: Why does Larry wait until the Mayans come alive to lock them up? I know he's allowed to be stupid but he had a lot of time to sit and do nothing and I can see no reason to wait.
Continuity mistake: When Larry lifts up the cowboy and the roman emperor and places them on the bench, they move closer together between shots. (00:53:20)
Continuity mistake: The epaulets on Larry's normal jacket disappear and reappear between shots.
Continuity mistake: When Larry is talking to Erica about getting a job, they both drink glasses of water. In one shot, Erica is just about to drink from her glass, but in the next shot her arm is lowered down by her waist. (00:05:05)
Continuity mistake: In the end, when Larry meets up with Teddy Roosevelt, during that whole scene, the people in the background change positions, especially the guards in the blue cape.
Other mistake: When Larry takes Jed back to his miniature city, in the shot where the T-Rex almost hits Larry, watch Teddy's' horse. His head moves, following Larry and the cameraman. This cannot happen as the horse and Teddy had been already transformed into statues. (00:42:00 - 00:43:00)