* FridgeBrilliance: Sean mimics his father. In Jaws The Revenge, Sean has become the chief of the Amity Police. He's ''still'' mimicking Martin.
* The whale's eerie howls in the night? It's warning its podmates that there's a dangerous predator in the area.
* Why did the shark attack and eat Alex, when there were plenty of other easily available humans? Because Alex, on his float with his arms and legs sticking out, probably looked from below like a seal or a turtle. This is one of the major causes of shark attacks in real life, where sharks attack surfers when they mistake them for their natural prey.
* FridgeLogic: The scene after Hooper is shocked into dropping the huge shark tooth by the severed head in the hull of the boat consists of him and Brody confronting the mayor and demanding the beaches be closed. The mayor takes the absence of the tooth as the lack of evidence he needs to ignore their warnings - the two of them seem to forget they actually have ''stronger evidence'' in the form of the mutilated human remains aboard the wrecked boat! The reason for this gaping error is that the shot of the severed head was added by Spielberg at the last minute to wring "one more scream" out of the audience, but no script alterations were made to accommodate it.
** The first shark victim wasn't enough evidence why should a busted up boat and a busted up body inside be proof of a shark to the mayor?
** The mayor still hoped the (dead) tiger shark was responsible.
** If you notice, there are worms in Gardner's eye socket, meaning he had been dead for awhile, even longer than Christie. Combine this with the fact that the Mayor had declared the shark dead, and that Hooper was saying a shark of an entirely different species was responsible for their deaths, and he would have needed the tooth.
*** Those aren't worms, they are tendrils that attached the eye to it's socket.
** Gardner couldn't have been dead longer than Christine: we see him during the massive shark hunt. He's the one who rambles: "Wait'll we get them silly bastards down in that rock pile. There'll be some fun. They'll wish their fathers had never met their mothers when they start takin' their bottoms out and slammin' into them rocks, boy."
* The scene where Hooper dives into the water seems not-so-scary until the reveal of Ben Gardner's head, since he knew that the shark was not in the area due to his boat's radar. Until you realize that Brody doesn't know how to operate any of the gear and couldn't warn him if the shark ''did'' start to return.
** When Pippet the dog does not come back before the shark kills Alex. It is highly likely that the dog was eaten be the shark.
** When the shark charges towards Brody in the final encounter, scraps of flesh are shown around its teeth. This may have been the last we have seen of poor Quint.