Factual error: At the end when the shark is attacking the boat and the electronic device is used you can hear the shark roar. Sharks cannot produce this sound since they have no vocal cords.
Factual error: Sharks cannot "stand" up on the surface of the water like this one does in the end. (01:11:15)
Factual error: The shark follows Brody into the sunken ship (yeah, right) and eventually the chase ends with the shark at the end of a very narrow passageway, with no room for it swim further forward, and no room to turn. Since the rigid nature of a shark's pectoral fins means that they cannot swim backwards this one would be stuck. And since Great White sharks have to constantly swim in order to breathe, the movie really should have ended right there.
Factual error: The shark that attacks the Brodys in the Bahamas is presumably the same one that kills poor Sean Brody on Amity Island (that poor kid can't catch a break). Ellen departs for the Bahamas after Sean's funeral and the shark follows shortly thereafter. So, the shark swims from Amity, an island off the North Atlantic Coast, down to the Bahamas in order to stalk Ellen, Mike, etc. in a matter of days. Hmmm. As Matt Hooper said in the first film, "fast fish".
Answer: When Bruce IV eats Mario Van Peebles, it also eats a device that they use to give it an electric shock by remote control. This makes it leap out of the water. The last time they do this, the long pole on the boat's bow impales it.
Grumpy Scot