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)Super Grover
Visible crew/equipment: While Quint tells of his experience with the U.S.S. Indianapolis, in the close-ups of Brody a crew member's arm with a watch is clearly visible moving in the reflection on the window, just behind Brody, particularly when Quint says, "Anyway, we delivered the bomb." (01:32:55)Super Grover
Continuity mistake: When the shark slams into the cage and makes Hooper drop his weapon, it shows the underside of the shark; look at the its mouth. When the shark is about to slam into the cage again its mouth isn't the same size as it was before. You can tell that they used a real shark when they showed the underside. (01:54:15)
Revealing mistake: When Quint begins singing 'Ladies of Spain' while Bruce is chasing the Orca into the shallows, he turns slightly to his left and looks over his shoulder. When he does, you can see that the barrels are actually being towed by the Orca, due to the wake of the line doing the towing.alfredodedarc
Revealing mistake: When the boy is attacked at the beach a man says "did you see that?" The woman behind him wearing the hat sits up with everyone else then looks directly at the camera and smiles instead of looking at the attack.
Character mistake: Captain Quint tells Hooper and Brody that the USS Indianapolis delivered "the Hiroshima bomb" in 1945. This is a myth that has persisted for decades and right up to the present. To prevent it from being lost in one piece, the Hiroshima bomb was actually delivered in pieces by various means to Tinian Island, where the parts were reassembled before it was carried aboard the Enola Gay to its target in Japan. The USS Indianapolis delivered only the detonator for the bomb. (01:29:00)
Revealing mistake: When Brody is stabbing Jaws at the end with the harpoon, you can see air bubbles under the rubber skin on top of Jaw's head - air bubbles or the blood bags.