Plot hole: There are six metal bars mounted around the circumference of the water wheel's axle. In the wheel's interior, when Jack frees himself he lands on his feet, begins to run and promptly hits his head on one of those mounted axle bars, then falls out. Moments later, when Jack returns and runs in the wheel, he is shorter (way more than a foot) than all six of the mounted axle bars spinning with the water wheel, which would make that previous shot impossible, however humorous it is. (01:52:40 - 01:53:55)
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)
Plot hole: Where did Cross get the blood on his hands? The gloves were clean of blood after he looked at the teeth and removed the gloves, so where did it come from?
Plot hole: The whole plot of the first "Brother Bear" was that Kenai had to go to that mountain to become human. But at the end of this movie, the spirits were about to change Kenai back into a human in the middle of a cliff, which makes the entire first movie completely pointless.
Plot hole: When Kate went to the aid of the man lying in the street, she was very upset about his death. Would she not have got his name being that she works in a hospital? Also she could have easily Googled him in 2006 to find out where he was or that he had died already. It seemed an obvious ending that she would save his life to change history.
Plot hole: In the river scene, Betameche states that his pocket knife doesn't have rope, as it's only available on the smaller model. Yet, around 10 minutes later, Princess Selinia is pulling a retracting rope from the pocket knife, allowing them to abseil down. (00:45:00 - 01:00:00)