Trivia: There are two different endings to this movie. In the first one (released on video and DVD in the US), the shark (inexplicably) explodes after being rammed by the boat and sinks to the bottom in a reuse of footage from "Jaws." When the camera cuts back to the survivors floating in the water, we see that Mario Van Peebles, though badly wounded, is alive after all. In the second ending (which can be seen on American Movie Classics in the US), Mario Van Peebles does not survive his fall off of the boat; when he falls, he lands in the shark's mouth and is killed. Also, when the boat rams into the shark, it does not explode but is more "realistically" impaled, blood pouring from its mouth as it dies. After the survivors are knocked off the boat, there is a shot of ship and shark sinking to the bottom, prow of the ship stuck in the side of the shark.
Trivia: The woman who greets Thea and makes her food when Michael and his family arrive in Amity is Mrs. Kitner, mother to the second victim in the original "Jaws".
Trivia: Because Michael Caine was shooting his scenes for Jaws 4, he couldn't collect his Best Supporting Actor Oscar for "Hannah and her Sisters." Roger Ebert later joked about Caine not being able to return after Ebert saw the film and thought it was incredibly bad, saying Caine wouldn't have wanted to return if he went to the ceremony.
Trivia: Joseph Sargent was called one night to direct the fourth Jaws film with no script, and yet somehow they made and released the film 9 months after that.