Jaws is my all time favorite film! Besides the facts that have already been posted, here's a few more...
1. The animosity between Hooper and Quint on screen was not acting. Robert Shaw and Richard Dryfus couldn't stand each other. Shaw constantly f'cked with Dryfus on set, telling him things like "Well Richard you know, if there's a large demand for short, Jewish, character actors you could potentially have a pretty good career." LMAO!
2. The tiger shark that the locals caught and mistook for the killer shark was not a prop. It was in fact real. It had been caught just off the coast of Martha's Vinyard (where it the movie was filmed) during shooting so they used it in the scene.
3. The opening underwater scene where you first hear the theme song was originally supposed to be shot from within the shark's mouth but technology at the time just couldn't make it work.
4. Ellen Brody was played by Lorraine Gary. She was the wife of Universal Studios executive Sidney Sheinberg who had basically "discovered" Stephen Spielberg. While Lorraine is great in the role, her getting it was obviously an act of nepotism.
5. Scuba tanks do not in fact explode when shot. This was a huge point of contention on set between Spielberg and Jaws author Peter Benchley. Peter was sure that movie-goers would call bullsh_t on that fact (in the book, the shark just dies from it's wounds). However Spielberg insisted that movie-goers wouldn't care and it would be a fantastic ending to the film. I guess we know now who was right!
6. The shark in Jaws was named "Bruce" after Spielberg's lawyer Bruce Raymer.
7. The FX company that built the shark was also responsible for building the giant octopus in Disney's 20,000 Leagues Under The Sea.
8. The underwater scene where Richard Dreyfus sees the fisherman's head roll out of the hole was completely spontaneous. Spielberg did not tell Dreyfus that was going to happen in order to get a real response from him.