Continuity mistake: When Kelly is on the boat with Hank and the soon to be headless deputy, her green vest (life-jacket) is fully unzipped. When we see her immediately after she's been knocked in the water, her jacket is zipped almost all the way up.
Continuity mistake: In the opening scene at the beginning of the movie, the Sheriff and Fish & Game diver are going to tag beavers. There is a clear shot of the diver under water at the beaver dam with a white oxygen tank. Shortly after he is attacked, part of his suit surfaces in the water with a black/gray oxygen tank, not white.
Continuity mistake: After Kelly has finished talking on the mobile phone at the lake she puts the antenna down then in the shot immediately following puts it down again.
Continuity mistake: The Crocodile changes size in between takes and shots. Example: In the scene where Hector is swimming with it, from a top view, it's head is small. When it goes to view from underwater, it's head is bigger than Hector.
Continuity mistake: During the scene where Hector finds himself with the 30 foot crocodile, he blows up a raft and leaps on board his helicopter and takes off to find that the crocodile has bitten down on one of the pontoons. The crocodile clearly bends the pontoon with its teeth. But when the helicopter finally goes airborne, the pontoon is fully intact, only the tarp covering is ripped.
Deliberate mistake: While Hector is in the water with the crocodile, he yells to the female officer to start the helicopter by turning the key. It takes a lot more than just the key to start a Bell Jet Ranger helicopter. Fuel shutoff valve, throttle, key, and the main rotor doesn't start rotating until the throttle on the collective stick is turned to a specific position.
Revealing mistake: During the opening sequence, when the fish and game officer is just about to be attacked while looking inside the nest, there's a clear reflection of his lower body as the camera moves closer from behind him. This reveals the diver is in some type of tank, otherwise, this could be a piece of equipment, like Plexiglas (or similar,) put in place within a real body of water for filming purposes.