Revealing mistake: When the baby shark smashes into the gate, not only is it a dummy by the way it looks, but the head actually compresses back into the body on impact.
Revealing mistake: When the baby shark dies it is an obvious fake rubber shark with no movement before it died and no reaction from the watching crowd.
Revealing mistake: As Mike and Kathryn are underwater with the submarine, they pass the control room, and in the next shot, as the submarine turns around, the front of it suddenly goes transparent. (00:32:00)
Audio problem: Near the end of the film when the shark is in the control room he eats a man underwater. The man is heard to scream and cry out, and you can hear him taking breaths in between screams despite being underwater with no breathing equipment.
Revealing mistake: When the shark goes on a rampage at Sea World, whenever the fin goes above water, it is blatantly obvious that the fin is fake, and it is doubly obvious in some shots when we can see the welding line running right down the fin where the crew fused the two sides of the fin together.
Factual error: In the scene near the beginning of the film where a diver gets eaten by the shark, an unattached arm is left suspended in the water. Not one drop of blood was spilt into this water.
Revealing mistake: About two-thirds of the way through the film, there is a wide shot of Jaws swimming. Keep in mind that a shark swims by the moving of its body and tail. It's quite obvious to see that Jaws is a matted-in puppet as his tail moves only once and he is propelled a long distance. Also note the fact that the tail move is quite mechanical and not the easy motion a real shark would make, and his body doesn't move at all. The shark in Shark Attack 3: Megalodon looked better than this.
Revealing mistake: Matte lines are visible on the submarine as Mike and his girlfriend drive it through the reef.
Revealing mistake: Very obvious fake dummy when Mike and his girlfriend view the dead body.
Revealing mistake: Matte lines are visible around Jaws when he crashes into the window of the control room.
Continuity mistake: In the kitchen scene when Mike and Sean are eating breakfast, the phone cord hanging behind Mike keeps changing from being loose and free, to all twisted and tangled. (00:26:40)
Continuity mistake: In the breakfast scene, as Mike walks over to the table with the pot of coffee, the amount in the pot changes from barely full to almost full to the top as he sits down. (00:26:35)
Continuity mistake: In the breakfast scene with Mike and Sean, the angle of the Tropicana juice carton keeps changing. (00:26:10)
Continuity mistake: Before the film ends, Kathryn is right next to the dolphin, touching its rostrum. A shot later from a different angle, the dolphin is suddenly two metres away.
Continuity mistake: Before the film ends, when Mike and Kathryn emerge from the water, it is dawn; two seconds later, it is suddenly broad daylight.
Continuity mistake: When Kathryn caresses the orca, the position of her hair is inconsistent: in some shots it is tucked behind her ear, while in others it falls loose, changing from shot to shot. (00:10:46)
Continuity mistake: Before Dan rides the jet ski, a man removes the oxygen tank from a scuba diver and places it away, behind him. In the following shot, when Dan is already riding the jet ski, the tank has reappeared and the man is shown removing it again.
Revealing mistake: When Shelby's corpse shows up in a Ben Gardner like jump scare, you can tell that the hair is not attached after they made a mold of Harry Grant's chest and face and edited it.
Continuity mistake: After the big shark dies Mike and the blonde girl are calling the dolphins, in one shot it's dawn and it's dark but suddenly in the very next shot it's completely daylight.
Revealing mistake: When the shark bites the fish in half just before the opening titles you can see the back of the fish tank the shot was being filmed in.
Answer: The lagoon was part of the theme park. Artificial with specific mammals inhabitants inside, warm and friendly.