Factual error: In different scenes, with the mama Megalodon, the teeth shown are around the size of the people themselves. In actuality, the Megalodon's tooth is only a bit larger than the size of your hand.
Factual error: At the start of the film, a shark is attacking and killing a diver who is presumably at a depth of 1,500 feet. However, the shots actually show a great white shark eating a diver on the water's surface.
Factual error: When the lobster is caught off the coast of Mexico, at the start, it has large claws, such as found in Maine. "Spiny" lobsters, without claws, are found in Mexico.
Factual error: The megalodon tooth shown in the film is actually not from a megalodon. It seems to be related to the genus Isurus, the mako shark, or maybe the Cosmopolitodus, which most scientists identify as the ancestor of the great whites. The tooth doesn't have a v-shaped root, it is laterally compressed and lacks a scar and fine serrations.
Factual error: During quite a few underwater shots, there are no air bubbles coming from any of the divers' air tanks, which likely reveals that those shots were filmed somewhere else.
Factual error: Sharks are attracted to electrical fields, but fiber optic cables, such as the ones used underwater in the film, do not emit any electromagnetic radiation for the shark to actually be drawn to.