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)
Continuity mistake: After the Orca breaks down for good, Hooper goes into the shark cage to try to kill the shark. The shark proceeds to completely trash the bars on one of the sides. After Hooper escapes to the sea bottom, the shark is attacking the top of the cage, but the bars are now intact. [Extra info: The scene with the bars intact actually shows a very real shark that got caught in the line(s) holding the intact cage. When they raised the cage it was still caught in the line(s). They inserted this footage after the scenes with Hooper and Bruce where the cage got trashed.] (01:55:20)
Continuity mistake: Check out the scene where the girl gets attacked at the start - keep your eye on the clouds and how they move around. (00:03:10)
Continuity mistake: While Brody watches the woman in the water, before Alex is attacked, there is a blue and yellow raft in the cabana behind him. In the close-up of his face, just before Harry's black capped head pops out of the water, the raft is gone. Then when Ellen massages Brody's neck the raft is back. The cooler and other assorted items change position between shots as well. (00:15:00)
Continuity mistake: When the shark is harpooned to some rope, Brody & Hooper tie the rope to the stern cleats, causing the boat to be dragged backwards. Quint gets a machete to cut the rope to limit the boat's damage. At this point the sea is somewhat choppy. He throws the machete making it stick into the edge of the boat. The sea in the background is now completely calm. (01:44:25)
Continuity mistake: The word ORCA on the back of the boat continually changes from shot to shot varying from very rusty letters to shiny letters.
Continuity mistake: Just before the Kintner boy is attacked, when Chief Brody is sitting on the beach watching the water, he speaks with the old man called Harry. In the close-up shot of Harry the chin strap of his rubber cap hangs down loose at his chest, but in the side shots the chin strap is tucked up at his ear (seen when Harry stands up). (00:16:00)
Continuity mistake: After the first barrel pops up, Hooper and Quint gather up the rope while at the stern. The existence of rope in each of their hands changes abruptly between shots. Particularly when Quint holds the rope only in his left hand in the wide shot, but in the next dramatic close-up as it leaves a rope burn, he grips it in both hands. (01:37:30)