When Brody and Ellen are sitting at the kitchen table on the morning after Brody was fired, when Ellen stands up to talk to their house keeper, the shadow of a crewman holding a boom mic is visible on the wall on the right of screen, while the shadow of the boom mic can be seen above the doorway.
The shark in Jaws smashed through the left side of the Orca, but at the beginning of this film when the divers find the wreck of the Orca, the left side is untouched. We also see a sign saying "Orca" under the pulpit of the boat, which was not there in the original film. The only place which the word "Orca" appeared in, was at the back of the stern.
When Ellen Brody is hugging an hysterical Tina on board Tina's boat, she holds her arms in an embrace, before putting her hands around Tina's head. In the next shot she is seen again holding her arms in an embrace as if the second shot hadn't happened. The shot after this shows Ellen again holding Tina's head.
After Mike gets knocked cold during the shark attack, he slides off the boat and into the water, but when the shark flips it over a moment later, not only is he back on board, but he is sitting upright as if he is awake.
When Tina and Eddie discover the dead whale on the beach, they are standing on a large sand dune which is right beside the whale. When Chief Brody and Dr. Elkins arrive on the scene, the sand dune is no longer there.
When Brody is driving by the beach and sees something floating in the water he sits down on the beach to take off his shoes and socks before wading in. As he starts to sit down you can see he has a wet bottom from obviously doing the scene before.
When the shark attacks Tina's boat & Eddie is thrown overboard, Tina spots the shark & mutters "Jesus" her hair is all disheveled & messy, when she turns towards Eddie to shout to him swim, her hair is perfectly styled & neat.
When Brody is heading towards the teenagers near Cable Junction, we see his view from the direction he is approaching them from. In the shot seen from Cable Junction, Brody approaches them from behind, which is not the direction he was coming from originally.
When the shark attacks the patrol helicopter, one shot of the helicopter going under reveals the shark with his head facing away from it. Presumably, he should be facing the left side of the helicopter if he drags it down by the pontoon.
The position of the towel Chief Brody has on his shoulder changes (as evidenced by the pattern) when he wakes up the morning after being fired as he walks down the hallway and opens doors looking for his son.
In the shot where the camera is on the shark's back as it's heading toward Mike while his friends try to lift him up out of the water, a large crew boat is visible in the background behind one of the sailboats (upper right corner of the screen)
Before the group of recreational scuba divers are surprised by the shark, one of them encounters and tries to trap a spiny lobster. The spiny lobster species is native to Florida and the Caribbean, not in northern areas such as Massachusetts or New York State where the movie takes place.
Dr. Lureen Elkins states the length of the beached whale in meters and the length of one of the dimensions of its bite wound in centimeters. A second later she is shown trying to measure the other dimension of the wound and the tape measure is clearly shown to be marked only in feet and inches.
When Brody sets out in the police boat to find the boys with his wife and the deputy, he has a green MA1 type bomber jacket on (which he left the house wearing). When they find the girl hiding in the drifting sailboat, he takes this jacket off and wraps it around the girl and hands her over to his wife. His wife, the girl and the deputy then wait for a nearby boat to take them back to land while Brody continues on by himself in the police boat looking for the other kids. He does not take his jacket with him and is seen only in his T-shirt and shorts. However, at the end of the film, Brody is wearing a green jacket again. However, this is an army type jacket that is a completely different style to the MA1 jacket, and has front breast pockets and epaulets (straps) on the shoulders which the MA1 jacket did not have. It is possible that this jacket was already on the police boat beforehand and Brody simply found it and put it on as the weather was changing.
When Brody fires six shots at what turns out to be bluefish during the crowded beach scene, he unloaded the spent casings from his revolver as if he were going to reload. He doesn't reload, but he stoops down and picks up 9 casings off the sand. However, upon closer examination, you can see unspent bullets on the sand with the empty casings (Sean picks at least one up). It is likely that while Brody was struggling to reload with fresh bullets he had in his pocket, he dropped them onto the sand, at which time he was told that he was only firing at a school of bluefish.
The old lady is looking straight at the boat when it explodes, yet she fails to see the shark on fire next to it before it drops back underwater. Similarly, she hears the sound of the boat moving earlier, as does Tina, yet neither of them (or Eddie) hear the boat driver's screams or the sounds of the boat being destroyed by the shark. In actual fact, the old lady had a book in her hand when she first sees the waterskier's boat and no doubt got back to her book up until the boat exploded. Likewise, Tina was no longer in in sight of the boat once she returns to Eddie in the dunes. As for the sound of the shark attack, the shark itself does not make any noise and woman's screams would not necessarily have been as loud as the boat engine (even if they were, it could have been mistaken for the women having a good time rather than terror).
When the police launch spots the sailboat that Tina and her boyfriend Ed were using, there is no apparent damage to the wooden rim on the port side of the boat yet when the launch finally pulls alongside the sailboat, the expected damage is visible again. The damage is actually always there, it is just not as easy to see because of the angle of the camera is straight on to the line of the boat rim.
When the shark first attacked the kids, Jackie and Sean fell into the water but in the next scene later on they look liked they never did. However, we do not know how much time passed between these two scenes and it could well be that they dried off in the hot sun.
During the ceremony at the beginning, while Len is asking Ellen to check the bar, Brody looks at the camera for half a second while his eyes scan the room. However, this is not a character error as it simply shows Brody was scanning the entire room.
The opening shot of the kids group in the bar is mirrored. The chalk board writing is backwards, the Wurlitzer label on the jukebox is backwards, Andy's MIT shirt reads TIM. The whole first shot is mirrored up until the first cut with Michael at the bar. This is because the wall of the bar is made up of mirrors which is made clear when Lucy and Patrick (the couple drinking while linking arms) are seen together as you can see them and their reflections.
The police boat that Brody takes to rescue the kids has a registration number starting with "MS" - a police boat for Amity would be registered in New York, not in Massachusetts. However, it is never made clear exactly where Amity is and the first film implies it could either be in Massachusetts or New York (as referenced when Mayor Vaughan states if people cannot swim at Amity's beaches they would go to other nearby beaches at Cape Cod, The Hamptons or Long Island).
(at around 1hr 43min) The shark brushes against Lucy and it's sharp scales cut her above the left hip. While sharkskin is capable of doing this, it is only rough from tail to nose. Nose to tail, it is actually relatively smooth. However, the sheer size and speed of the shark brushing by her could still cause some damage to soft human skin tissue.
When they find Tina's sailboat adrift, the Police Deputy is seen tying the boats together, but then Brody hails a passing boat and takes off without untying the police boat from Tina's boat. However, when he is asking Hendricks which direction the other kids are heading, he is clearly loosening the rope as he speaks. Although the rope is still there as he walks over to the steering controls of the police boat, the loosened end of the rope could likely have fallen into the water as the smaller boat began floating away from the police boat as Brody pulled away.
When the kids are lifting the unconscious Mike Brody out the water as the shark comes out the water and runs along the side of the boat you see the main pneumatic piston in its mouth if you look carefully...that and the mouth gets all bent out of shape when running alongside the boat.
In one of the sequences where the shark attacks the kids, underwater shots of the shark (meant to be a great white) are actually stock footage of a black tip shark. This is obvious, as you could imagine, from the black tip markings on the visible dorsal and pectoral fins. It is a smaller and less aggressive shark than the great white.
Near the end of the film, as Brody begins to climb out onto the power cable, it cuts to a shot of Andy and Larry, who swam to Cable Junction island, sitting on the rocks at the waters edge watching him. The entire set of "rocks" that they are sitting on are bobbing up and down in the water with them. This was due to the fact that the entire island was made from fiberglass and was build upon two large barges (see Trivia).
As Brody approaches Mike and his friends in the sailboat while searching for them. it's apparent that they are on the ocean from the wide shots. Also, in the wide shots, it's obvious that the weather is turning bad. However, in the closeup shots of the actors tying the boats together, not only is it now sunny and clear out, but there is suddenly a large bridge behind the three kids' boat that wasn't there a moment ago. Brody unties from the boat and the wide shot of him pulling away shows nothing but ocean and impending bad weather again.
When the recreational divers are scrambling to get back to the boat after being attacked by the shark, one of the divers gets injured and has to be attended to by the others. This scene was shot in Choctawhatchee Bay near Destin Florida, nowhere near where the fictional Amity island is supposed to exist in the New England area. As the divers pick up the injured diver to carry him inside the boats cabin, the shark swims by in the background. In the far distance, the Mid Bay Bridge between Destin and Niceville Florida can easily be seen.
When Brody leaves his police car and walks down to the beach to look for evidence, he looks into the water then sits on sand to remove his shoes. As he sits, you see that the seat of his pants are already soaked. The scene was apparently shot over, and his pants were still wet.