Continuity mistake: On the dock, Charlie and Denherder wrap a link chain around the corner piling, which is yanked when the shark takes the roast bait. In the close-up the chain is pulled taught from the front and breaks free, but in the next wide shot the chain is slack and being pulled from behind the links around the piling. (00:26:25)
Continuity mistake: In the scene where Brody blows up the shark, off in the background there is land in some shots and then no land in others. At one point, there is land about half way across the horizon, then there is land across the whole horizon, and then no land, it varies shot to shot.
Continuity mistake: When the three men are in the cabin of the Orca at night, Quint is leaning forward against the table and is drinking something. In the next shot, as Hooper feels the cut on his forehead, Quint is turned towards the side leaning on the back of his seat, but in the next shot of Quint, he is leaning forward again in the same position as the first shot. (01:26:30)
Continuity mistake: While Brody starts to chum, Quint goes to the cabin to sit and work on the fishing reel, and the portable stove is visible to his right. Then when Quint speaks with Amity Point light station the pots, kettle, etc., on the stovetop are positioned differently and now there is an additional white pot. The hanging net has fewer things too. (01:20:50)
Revealing mistake: When Hooper is in the cage the regulator hose is to Hooper's right (viewer's left when facing him). However, when the shark first appears and passes Hooper, in the shot facing him the hose is now to Hooper's left (viewer's right), and the word "repeater" on the poison shark dart is also backwards. This is a flipped shot. (01:53:30)
Continuity mistake: In a deleted scene, Quint walks into a music store to buy piano wire for his fishing reel. The woman behind the counter is giving a young customer a new clarinet reed and says, "It's a number three. It should be softer than the number two you had." Clarinet reed hardness is categorized with one being the softest and five being the hardest, so a three would be harder than a two.
Continuity mistake: When Quint stands beside the stove at his place, the stove is positioned a particular way in front of the wall. When he gives Hooper the rope, the stove is farther down against the wall and the wall behind the stove differs (note the panels), as do the roll shades on these windows. (01:07:00)
Continuity mistake: When Brody is in the flooded cabin as it tips, at the start of the shot where the shark makes its smashing entrance, we actually hear Brody's loud footsteps on wood, as we see his waist and legs run from aft to forward in the cabin; though in the previous shots Brody is more than waist level in the water, already standing towards the bow. (01:57:55)
Continuity mistake: The cleats are entirely different in many shots; they keeps changing from flat top, long, shiny silver with a wide base, to curved top, dull silver with a narrow base. When Brody unties the wrong line and when he wets the fishing reel it is the shiny flat top cleat on the transom. Yet, when he and Hooper tie off the lines the cleats are curved top. Also, the two metal plates and two metal hoods that are near the cleats repeatedly change from being very rusty, to not rusty at all. (01:17:40 - 01:22:00)
Continuity mistake: The zinc oxide on Brody's nose either appears or disappears between shots. When Brody pulls the wrong line causing the air tanks to roll, he falls back and there's zinc oxide on his nose, yet when he puts another chum marker in the water the zinc oxide is gone. Another example; when Brody says, "I can go slow ahead. Come on down and chum some of this sh*t," in a close-up there is no zinc oxide on his nose, yet when Quint remarks that it's a twenty five footer, suddenly he has zinc oxide on his nose. The amount of zinc oxide also changes between shots, when he wears it. (01:13:05 - 01:20:00)
Continuity mistake: After Hooper says, "Yeah, he's eating his way right up to us," Hooper and Brody shout for Quint. As Quint rushes to the stern, in the interior shot looking out the window the toolbox and books are in front of the window. When the barrel flies into that cabin window, smashing it, ALL the books are different, things are positioned differently and a thermos suddenly appears. But after the engine burnout, when Quint surveys the damage in the cabin, the books are same as the first shot and now they're actually upright. (01:43:40)
Other mistake: In the scene at the dinner table, when Brody's son is copying his movements, after Brody puts down his glass to cross his fingers, you see his son cross them before Brody does. (00:39:20)
Character mistake: During one of the shark scares at the beach, Chief Brody is running along the shoreline telling everyone to get out of the water. There are several frames where the Chief and a man with a moustache are at the water's edge. If you look closely you will notice that the man is smiling and laughing and other people laugh as well. (00:17:30)