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.