Factual error: At the end when the shark is attacking the boat and the electronic device is used you can hear the shark roar. Sharks cannot produce this sound since they have no vocal cords.
Factual error: Sharks cannot "stand" up on the surface of the water like this one does in the end. (01:11:15)
Revealing mistake: Toward the end, when they have killed the shark and are all floating about in the water, you can see that the horizon is a painting. The water is even lapping up against it. (01:20:30)
Factual error: The shark follows Brody into the sunken ship (yeah, right) and eventually the chase ends with the shark at the end of a very narrow passageway, with no room for it swim further forward, and no room to turn. Since the rigid nature of a shark's pectoral fins means that they cannot swim backwards this one would be stuck. And since Great White sharks have to constantly swim in order to breathe, the movie really should have ended right there.
Revealing mistake: When the shark is attacking someone under the water you can see a hole in the shark and divers fins showing that it's a puppet.
Revealing mistake: During the sequence when Michael has his underwater motorcraft and the shark attacks him, you can see in certain long shots the machine which works the shark protruding from under its tail.
Continuity mistake: In one of the final scenes in which the shark is attacking, the colour of the water is not consistent in the background. In one scene it is light blue, and in the other it is much darker blue.