Continuity mistake: In the close-up of the stern cleat as the shark pulls on the line, there are two large metal 'L' shape brackets screwed onto the corner of the wood of transom. Amazingly, these large brackets are not screwed into the wood in the close-up, as Brody winds the line round the cleat just a moment earlier. The metal brackets repeatedly appear and disappear. (01:42:30)
Continuity mistake: When Hooper and Brody tie off the stern cleats, the amount of line, and the way the lines are wound round the cleats, varies in the following shots. (01:42:35)
Visible crew/equipment: After tying off the cleats, the shark pulls Orca causing it to tip. As Hooper and Brody fall backwards onto the deck, in this close-up the white tape mark is visible on the black anti-slip mat - where Quint will land the machete in a subsequent shot. (01:43:00)
Continuity mistake: As the shark pulls on the lines tied to the stern cleats, the boat tips to the side and in the wideshot the emblem on one of the air tanks faces the side. Yet, in the next close-up as they hit the ladder, both face front. (01:43:05)
Continuity mistake: After wrapping the lines round the stern cleats, Quint yells, "Stand away from those stern cleats!" In the wideshot Quint stands at the wheel on the bridge deck, facing the bow, but in the next close-up he stands beside the foremast, below the crow's nest, facing the stern. (01:43:05)
Continuity mistake: Quint remarks, "Back home we got a taxidermy man. He gonna have a heart attack when he see what I brung him." In the shot of Orca's stern, just prior to this comment, the two attached yellow barrels are very worn, with many black marks all over. Yet, in the shot right after, both yellow barrels are almost entirely yellow - quick paint job. Throughout the Orca scenes the marks on all the barrels change many times in consecutive shots. (01:43:20)
Continuity mistake: After Hooper and Quint come up from the engine room, there are grease stains all over the front and back of Hooper's blue sweatshirt, that disappear, reappear or keep changing throughout the following shots. (01:43:35)
Continuity mistake: The chum markers, with the yellow flags, disappear and reappear on deck, in consecutive shots within the same scene. For instance, in the wideshot when Quint, Brody and Hooper are splashed and Quint shouts, "Untie us! He'll pull out the transom!" they are gone, but are back in the next shot of the deck. They keep changing positions as well. (01:43:40)
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: The positions of the harpoons - two at the dorsal fin and one under the mouth - change on the shark's body and are actually gone in quite a few shots. (01:43:50 - 01:56:45)
Revealing mistake: After Hooper's comment, "He's working his way up to us," Quint rushes to the stern and shoots another line into the shark. In a very tight close-up of the shark's gills it is very apparent that they are just wide carved ridges, with no slits whatsoever, to even attempt to give the illusion that they are real, like in other great shots of Bruce. (01:43:50)
Factual error: Right after Quint shoots the third barrel into the shark, the shark swims towards the camera with his mouth open and you hear a roar. Sharks do not roar since they have no vocal cords. (01:43:55)
Visible crew/equipment: Just before the barrel smashes the cabin window, as Quint shouts, "Untie us! He'll pull out the transom!" the reflection of the crew's swaying vessel is visible in the window of the cabin, behind Hooper. (01:44:00)
Revealing mistake: The ropes from the two barrels attached to 'Bruce' the shark are tied to the stern cleats, but then Bruce pulls on the ropes and starts to drag the boat sideways and nearly submerges the stern of the boat. As the boat is being pulled sideways by the ropes, they are both shown to have quite a bit of looseness, or slack in them. How can the boat be pulled like that if the ropes are not taut? (01:44:05)
Continuity mistake: After the two barrels are tied off, there is at least twenty feet of line between the barrels and where it disappears into the water. When the next harpoon is shot (the barrel shatters the cabin window) and the shark pulls Orca, that last barrel trails way ahead of Orca, its taught line being extremely shorter than the lines leading to the two other barrels, though the shark pulls them at the same time. However, once the cleats break off, the length of the three lines are identical in length. (01:44:15)
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: Quint embeds his machete into the wood at the side of the boat, but in the following wideshot the machete is gone. Then as Orca starts to move, when Hooper says, "He's chasing us, I don't believe it," the machete is back. But when the shark leaps onto the boat the machete is gone again, and then as the shark devours Quint the machete is back for him to grab, so he can valiantly stab the shark. (01:44:30)
Continuity mistake: When Chief Brody is standing on the boat, almost ankle deep in water, he throws down the pump and is about to climb up the ladder. In the next shot, while he is on the ladder, the shark (we presume) hits the boat making it list to the right and the deck is dry. (01:44:30)
Continuity mistake: Quint slams the machete into the wood beside the side cleat, and rigging lines. However, when the shark joins them aboard the boat and Quint is sliding towards its mouth, the machete's position changes - it is farther down towards the stern, note the black anti-slip mats. (01:44:30 - 01:57:00)
Audio problem: As the shark is towing the Orca, Hooper, Brody and Quint are at the stern cleats with the water splashing up in their faces. Their shouting does not match their mouth movements. Particularly when Hooper shouts, "It's impossible! It's impossible!" he is sticking his tongue way out, making it rather difficult to shout anything at all. (01:44:35)
Answer: Possibly a scar from having his appendix removed, I've been told.
The appendix shot is Brody - he is feeling inferior as the other two share tales of the sea and the only scar he has is from his appendix being removed.