The reporter on the beach is Peter Benchley, who wrote the novel "Jaws," and also co-wrote the film's screenplay.
The name Ben Gardner comes up in the film when Brody asks if Ben caught the tiger shark, and when Brody and Hooper find Ben's battered boat (which leads to Hooper seeing his severed head), though Ben is never introduced in the film. Ben does make two unidentified appearances while alive. When Hooper arrives in Amity, Ben is the first man to greet him at the dock, and at the start of the shark hunt Ben is the first man shown in a moving boat, as he complains about the other fishermen.
The man's voice on Quint's radio is Steven Spielberg.
Brody's dog actually was the real life pet dog of Steven Spielberg.
Brody's line, "You're gonna need a bigger boat", was actually a total ad-lib. The director wanted a real reaction to the shark popping up really close to him, so they didn't tell Roy Scheider that it was going to happen. It was a total surprise. Not only did he react naturally, it scared him so badly that he forgot the correct line. So, when he looked at Quint, he ad-libbed, and they left in the movie. (It was number 35 on the top 100 Most Memorable Movie Quotes list).
During the scene where Dreyfus' character is underwater in a protective case, Spielberg used a real shark, which was much smaller than the mechanical shark. So they used a little person/dwarf to stand in for Dreyfus in the scene.
After the shark blows up and they show it under water you can hear a sound, taken from "Creature from the Black Lagoon ". It was also used when the truck was falling off the cliff in Duel, another Spielberg movie.