Continuity mistake: When the shark is brought up to put the needle in his head, it bites off Jim's arm, leaving only a bit left there, but when they are wheeling him to the helicopter you see that he's got more arm than before. (00:33:50 - 00:35:25)
Continuity mistake: Towards the end of the movie, the Preacher stabs the shark in its left eye with his cross, causing it to bleed. In the later scene, when shark returns to eat Susan, its eye is intact. (01:28:10 - 01:32:45)
Continuity mistake: The man with the cross has a wound on the left hand side of his head. Later in the movie it has moved down.
Continuity mistake: Near the end scene, when the three characters came to the surface, L.L. Cool J. was taken by the shark. When he was taken underwater and when he surfaced, the shark had him in her mouth on the right side. When they went under again and resurfaced, L.L.Cool J. was on the left of the shark's mouth. What? Did the shark not like him on the right side so she switched him underwater? (01:27:30)
Continuity mistake: When the shark rises above water with Jan partially in its mouth, its teeth are in about the level of her waist. As Carter grabs onto Jan, it moves its teeth up to the top of her chest. In the wide shot that follows, though, its teeth are back at her waist, then in the last shot of her being pulled underwater, they are up way higher again, at her chest.
Continuity mistake: While Carter is trying to save Jane, he is a few feet above the water. But in a shot from above you can see that he has to bend his body so as not to touch the surface. It would be very easy for him to reach her. But in the next shot, he's high above the water again. (01:06:25)
Continuity mistake: When Carter climbs the ladder to get out of the water after removing the licence plate from the shark's mouth, it shows a shot of his feet and he is wearing sandals. In the tank he was wearing swim fins. He talks to the big boss for a few seconds and the fins are nowhere to be seen. He then walks away with the fins in his hand. (00:08:55 - 00:10:20)
Continuity mistake: Carter pries open a door with a knife that is on as sheath on his leg. The knife breaks and he throws it away. In the final scene, when Carter and Preacher are laying on the wreckage, the knife is clearly visibly back in the sheath on Carter's right leg. (01:05:00 - 01:37:45)
Continuity mistake: When Preacher, Susan and Carter realise the only way out of Aquatica is to swim and they start filling the room up with water, Preacher holds out his hands to Susan and Carter. Carter then holds his hand out flat for Susan to take, and she puts her hand on top of his. However, in the next shot Susan's hand is on top and Carter's is underneath. (01:25:25)
Continuity mistake: In a scene near the end of the movie, Carter is swimming back to the wet lab through flooded passageways. At the beginning of the swim, his left shoe is completely untied - you can see both laces floating. In the next full body shot (where his shoes show) the shoe is tied again. (01:13:30)