Continuity mistake: When Carter is swimming down to the hatch, just after the technician has been eaten, you can see that when there's a shot showing what he can see, there's a straight beam of light presumably from his torch as that's the only source it could come from. However, when the camera moves back to see Carter swimming through the water, you can see that the torch he is carrying is moving around violently as he is trying to swim to the hatch. There's no way Carter could have held that torch straight enough for it to produce such a straight beam of light, especially since he's busy trying to escape being eaten by a freakishly smart shark. (01:17:35)
Factual error: After the doctor returns to her quarters and retrieves some papers, she is trapped on a table or a desk or something and she pulls out a wire that shocks and kills the shark. Isn't it convenient that the jolt ends for some reason right when the shark dies, even though the circuit would have stayed intact and she would have been shocked upon entering the water. (01:23:10)
Continuity mistake: At the start of the film when the man is trying to remove the licence plate from the sharks mouth you see a shot of him holding on to the fin on the huge shark from above the water. you can see the man is a good bit away from the mouth of the shark yet when we see the underwater shot he is just finger tips from the license plate. (00:09:20)
Continuity mistake: Look carefully at the licence plate when Blake removes it from the shark's mouth. It bends and flexes as though it's made out of rubber or even cardboard. Of course in the next scene when he throws it on the walkway, it's an ordinary licence plate. (00:09:30)
Other mistake: Near the beginning of the film, Carter asks Tom how high the fences are, then he tells them to make them higher, and Scoggs confirmed they were raised, but you can see that the fences never get any higher.