Corrected entry: Brody wears his badge on the right of his right chest, whereas all New York and Massachusetts law enforcement officers wear their badges over the left.
Corrected entry: When the kid is pumping up his boat and the shark rams it, he falls into the water head first. But when he gets on board the other boat, he still has his cap on. Highly unlikely.
Corrected entry: In the scene where Dr. Lureen Elkins is measuring the size of the Orca and its bites she does so in centimeters. The tape measure, however, reveals that she was actually using the inches side.
Corrected entry: In the scene where the shark attacks the boat, Tina's Joy, the boy falls over the side and the boat is pushed several yards. The sail falls off on the boat. We then see the boy in the water, then when the scene cuts back to the girl in the boat, the sail is back up again. (01:10:20)
Corrected entry: A shark's brain is roughly the size of a walnut. In general they aren't hugely intelligent creatures. There is no way the shark would have the intelligence to bring down the helicopter the way it did: the orange floating part was still, not shiny, with no contrasting colours, so a shark would have gone for the boat, which had black/white colours and was bobbing up and down, from the teens jumping.
Corrected entry: When Eddie is killed by the shark, he pulls down a piece of wood from the boat. When Brody finds Tina in the boat, it's completely intact again.
Corrected entry: When the shark drags the helicopter under the water the rotor blades, logically enough, hit the same patch of water that it (the shark) was occupying. Shouldn't it have been diced?
Corrected entry: When Larry is doing a handstand on his boat at the beginning of the film, a girl throws a light blue water balloon at him. Yet when Larry's friend in the boat picks it up to throw it back, it is now an orange balloon.
Corrected entry: The shark grazes the blonde girl swimming from the wreck to Cable Junction, but the blood from this should have made it crazy with hunger, instead it just turns away and swims off to circle the two left on the boat.