Goofs

Towards the end of the film when the blonde girl is knocked out of the boat and her male friend dives in to rescue her there are two clear errors. A) The location they enter the water is near the boat, however subsequent shots show them swimming a big distance and only just making it back in - clearly this was for suspense rather than reality. B) When she is thrown in her hair is tied back and up. When she goes in the water her hair is untied and flowing loosely in the water. Yet when she gets back onto the boat her hair is tied up again. Furthermore it must be magic hair, within the space of 2 minutes her hair is perfectly dry again and doesn't seem to have moved or suffered exposure to water at all.

At minute 22:38 the fishing boat is traveling at speed, just a few seconds later in the same scene, the boat is at a dead stop.

At 39:39 you get a quick glimpse of the boat captain holding a spear gun with blue elastic bands. At 40:20 it shows a closeup of the spear gun with green elastic bands firing the spear. Right after that, the spear gun is instantly reloaded and has blue elastic bands.

In the same scene the shark is seen eating the female coastguard/cop at the front of her boat, it is also shown approaching the boat from the rear.

In the first part of the movie when you see the full view of the shark it has four heads and a regular head. Later tail turns into a fifth head looking nothing like the earlier tail.

If the shark really has a head/mouth on the tail how is it able to actually swim forward with force. The tail fin is what propels the shark forward. I get that it can whip its tail to get forward momentum but it rarely does this, despite its super speed.

When they are all shooting off the stern while the shark is gaining on them, one of the rifles firing like a machine gun is actually a single-shot air rifle. A BB gun.

The image of the shark changes on the sonar, for most of the film it is a dot, towards the end of the film it has a shape.

While the shark has a sonar spear embedded in it you'll notice that sometimes it's there and sometimes it's not. It must be a magic spear.

There are times, especially at the start of the film where the shark only has 4 heads. It's apparent later on that the 5th head is on the tail but there are shots at the start of the film where this isn't the case, maybe it was added halfway through the editing process - but it definitely wasn't there during the first shots of the shark.

There are times where the visuals of the shark don't match where the sonar is putting it.

Towards the end of the movie, when the police are helping Red kill the shark, the police boat is attacked by the 5 headed shark. As Agent Black makes her way along the edge of the boat, hoping to see the shark in the water, the shark bumps the boat, knocking her off balance and into the water. A crew member's hand is clearly visible in the upper right hand corner of the shot.

When the female coastguard/cop is thrown from the boat towards the end of the film there is clearly a crew members hand in shot.

At the scene on the police boat after the female policeman is dead, the male runs back to the boat controls and you can see a male hand between the doors leading to the bottom deck.

In some shots of the boats in motion you can see the wake of the camera boat in shot.

Dr. Yost says that Cerberus was the two-headed hound of Hades but Cerberus is generally depicted as the three-headed hound of Hades.

The Day Off is displaying the red and white Diver Down flag whilst underway. The flag is to be displayed only when scuba divers are below to warn other boats to stay away.