According to actor Joseph Mascolo (Len Peterson), scenes were filmed by original director John D. Hancock that fleshed out his character; in particular, Peterson's mob connections, as mentioned in Carl Gottlieb/Dorothy Tristan's original screenplay. Once Hancock was fired, those scenes were discarded and never used.
When the crew had to go back to Martha's Vineyard for re-shoots in the Fall of 1977, many of the trees had already lost their leaves. The crew actually put fake leaves on the trees to make it look like it was still Summer.
Due to difficulties with weather and environment, most of the movie was filmed in and around Fort Walton Beach, Florida on the Northwest Panhandle. Many ocean scenes were actually shot in the Choctawhatchee Bay. "Cable Junction" was actually a floating set that was constructed for the film and kept docked at the Shalimar Yacht Basin when not needed and could be seen from the Garniers Bayou Bridge with its faux beacon flashing at night. Interior shots of the teen hang-out where they play pinball were filmed in the original location of the Hog's Breath Saloon on Okaloosa Island. This business relocated to a new facility in Destin, Florida in recent years after the first site proved very susceptible to hurricane damage. The original building was still vacant and derelict in January 2005.
The artificially constructed Cable Junction island set caused numerous problems during filming. The island was made from plastic material on a barge-like platform, which was so slick that it was difficult to traverse or even grab hold of, and this resulted in numerous retakes having to be shot. Due to its not being anchored down properly, it once drifted away in the ocean. In the making of Jaws 2 DVD documentary, director Jeannot Szwarc recounted the day when he was informed that his island set was "on its way to Cuba".
Many scenes had to be shot in the fall/winter months. As such, the actors had to suck ice cubes prior to takes to avoid having their breath seen on camera.
Ellen Brody tells her husband that Matt Hooper called to say he was on the Aurora. This is a reference to the first film. In the first film, Hooper turned down the opportunity to study on the Aurora in favor of studying the shark that was terrorizing the beach then.
Marc Gilpin (Sean Brody) claims that when they were shooting one of the scenes on the makeshift raft of wrecked yachts, they were being circled by a real hammerhead shark. All the actors were scared and began to scream and holler at the production crew who were filming that particular scene from a distance. The crew were oblivious to the danger and assumed the actors were simply 'in character' and gave them the thumbs up!
Dana Elcar was originally cast in the role of Len Peterson, which was much more darker than it eventually became. When Jeannot Szwarc took over the film and turned the character into a potential love interest for Ellen Brody, Elcar was let go and replaced with Joseph Mascolo, who had worked previously with Szwarc.
When shooting originally began (with John D. Hancock as director), Amity was envisioned as a near ghost-town, with boarded-up stores, crumbling facades on buildings and an economy in shambles after the events of Jaws. Hancock quickly ran into problems: First, the residents of Martha's Vineyard, where the film was being shot, refused to allow permission for their stores and houses to be boarded up. Secondly, his dailies were constantly being criticized by the studio for being "too contrasty and blue", with perpetual requests to lighten up the tone of the film. According to Hancock, however, his eventual firing was the result of a power struggle between co-producer Richard Zanuck and MCA chairman Sid Sheinberg, in particular Sheinberg's insistence that his wife Lorraine Gary (Ellen Brody) have a bigger role in the film. Zanuck adamantly refused, and Hancock's wife and co-screenwriter Dorothy Tristan eventually submitted a screenplay that did not include Sheinberg's requested changes. Moreover, Hancock ran into problems on the film with an unnamed female actress and had her fired; unbeknown to him, the actress was the girlfriend of an MCA executive. With a month of filming in the can, and 18 months in total already spent on the production, Hancock and Tristan were both fired, halting production on the film and leading to the eventual hiring of Jeannot Szwarc as director.
Roy Scheider did not originally want to appear in Jaws 2, but had recently left the production of The Deer Hunter, which led to conflicts with Universal Pictures to whom he was locked into a multi-film contract with. The studio agreed to forgive his leaving The Deerhunter if he did Jaws 2, which they would count as the two remaining films of his contract with them. Scheider agreed to the terms, but was resentful of his involvement from the onset and clashed frequently with director Jeannot Szwarc.
In a deleted scene, after the copter sinks, the shark attacks the pilot underwater. The sounds of the pilot screaming and the copter being damaged are the exact same sounds from Jaws when the shark attacks the shark cage and Hooper.
In the "final" draft screenplay, the helicopter pilot and Marge (the girl that rescues Sean) both survive. The pilot is able to breathe thanks to an air bubble in the copter's cockpit and Marge avoids the shark by diving underwater. The pilot spots Marge swimming underwater, goes after her, then guides her back inside the cockpit so they can share the air.