Factual error: When Charlie is in the small communications room of the underwater base, after the grenade blows out the window and the water is rushing in. The water would only come up to the top of the window, anything above that would be an air pocket and water would not go any higher, yet it got completely filled over Charlie's head.
Factual error: Naomi Doret, the woman who parachuted onto the island, is explaining about the outside world finding the wreckage of flight 815 "off the coast of Bali, in an ocean trench 4 miles deep". The problem with that statement is that Bali is nowhere near the Pacific Ocean, it's in the Indian Ocean. Oceanic flight 815 was a direct flight from Sydney, Australia to Los Angeles, US. That flight wouldn't go anywhere near the Indian Ocean or Bali.