20 Things You Didn't Know About Jaws 3D
4. When The Shark Explodes, An E.T. Doll Was In The Entrails
At the end of the film, the corpse of FitzRoyce is still caught in the shark's mouth, the corpses hand holding out a convenient grenade. Dennis Quaid uses a hook to pull the pin, blowing the shark to pieces, letting viscera float in 3D at the screen. It's much less impressive (if it ever was at all) on home video, which doesn't provide the traditional red and blue glasses.
You can't see it, because it was meant to be nothing but shark guts, but some of the shark's remains were made up of a brown, leather E.T. doll, an in-joke on-set to be sure. To audiences, it was just a bad special effect.