Plot hole: Anubis Warriors can only be killed by being beheaded. But during the final battle, you see several are killed by simply being stabbed.
Plot hole: Stuart establishes that there is only one of you and that when you travel through time you can repeat things, but it will be you and not your double that does it. But, at the end, when the Duke is going up the stairs and the uncle says "Where have you been...", the Duke is wearing the same clothes as the first time. Yet we see that he goes directly from the time portal to his house in the ballroom raiment of the later scene. Where did the old clothes come from?
Plot hole: The legend of the black knight (in this film) is that he can breathe dragon's fire. Jamal somehow rigs up his aerosol spray-can inside his helmet to shoot out the flames. However, there are three problems with this: one, how did it fit in the helmet? Two, how did he activate the spraying mechanism without his hands? And three, how did he even ignite the spray? (00:49:15 - 01:13:55)
Plot hole: There is no way that 'coast of Iceland' could ever have been mistranslated as 'coast of Ireland'. For this to have happened, they would have had to have thought that the 'C' rune was an 'R' rune, but they had already deciphered the word 'coast', so they knew what the 'C' rune was. The 'O's are the same rune and the 'A's are the same rune, plus there is one rune for every letter, so it it's a direct letter-by-letter translation.
Plot hole: When her father is taking the "shortcut" he somehow doesn't need to shift gears even though he has a manual transmission. At the speed he was at he should be in at least 2nd gear.
Plot hole: When the "Blue Bird" patient finally sees the Blue Jay, he starts excitedly shouting "Blue Bird! Blue Bird!" This uprising causes a riot in the institution, and in the immediate exterior shot of the building, everyone from all four floors already know and are staring out the window at the bird. Within the time-frame of the scene only the people on the floor which saw the bird would actually know about this. Psych ward floors are kept separated as it is even noted by an attendant when he said, "Do you want to go to the fourth floor?" which indicates that the floors are kept separate. This was deliberately done for dramatic purposes. (00:44:00 - 00:45:00)
Plot hole: If the ancient civilization wanted to stop people from ever using the power of the triangle again, why didn't they just destroy the triangle right then and there instead of splitting it in two and hiding the pieces? It would make sure that no one would ever get the power of the triangle and is easier than going to ends of the earth and creating all sorts of traps and challenges.
Plot hole: When Sully and Mike are talking in the toilets, during Boo and Sully's Hide and Seek game, Boo comes running in screaming and upset because she's just seen Randall, and he's not too far behind since all three can hear him talking offscreen to the CDA before entering the toilets, but how did Boo get to Sully faster than Randall without him seeing her, and how did Randall not hear her screams since they're all in the changing rooms which have an echo?