Factual error: Gorillas are almost exclusively herbivores. They have been observed eating small insects and grubs but nothing larger. So why does Isabelle eat a rat at the beginning of the film? The serum may have turned her into a crazed killer, as it does with Sebastian, but it hasn't changed the structure of her teeth and palate, biochemistry of her digestive system and so on, all of which would be required. She might kill or torture the rat, but she'd never eat it.
Factual error: The teens are traveling presumably along the Meadowbrook or Wantagh parkways, when they enter Jones Beach. They see a sign just before the beach entrance that says "New York: 93 miles", when Jones Beach is less than 15 miles from NYC limits and approximately 25-30 miles from Manhattan.
Factual error: In the beginning of the movie, the killer calls Cotton on his cell phone. When the killer hangs up on him, you hear a dial tone. When someone cuts you off on a cell phone, you don't get a dial tone. (00:02:40)
Factual error: When the husband swims to the other side of the lake to get some stuff in the truck, he lights his cigarette on one side and when he arrives on the other side, it's still lit. How could he swim trough the lake without getting his smoke wet?
Factual error: KCN does not causes you to internally bleed, so Yuka Nakagawa wouldn't have spat up blood and died like that in the lighthouse, but would have rather died due to cessation of respiration.
Factual error: When the group is travelling through the canyon near the end of the film, they are burning liquor to light the way, yet there is a lot more light than would be given off from this small flame. And none of it is flickering as would happen with a naked flame.
Factual error: The actress Sasha Barrese is credited at the beginning of the movie as "Sasha Berrese".
Factual error: When Bateman is in his apartment with his secretary, he points a large tool at the back of her head, unbeknownst to her. That is an air powered nailgun for installing plywood. The only way that one could be used is with an airhose and a compressor. The fitting for the airhose that sticks out of the bottom has been removed because it usually would point straight down and stick out about 2 inches. (01:02:45)
Factual error: After a new camera man is hired, Wagner, the camera man starts showing off to his fellow crew members that he invented "slow motion". In the next scene he demonstrates this by spinning the handle of the camera slowly. In fact this is not right, when the movie is projected the movie will be speeded up instead of slowed down.