Continuity mistake: During the scene where Quint, Hooper and Chief Brody are in the cabin at night and Quint tells the story of the USS Indianapolis, he puts his cap on the table, seconds later it disappears then later reappears. The fork on the plate also turns completely around, without anyone ever touching it. (01:25:50)
Continuity mistake: The seat that Quint sits in with the fishing reel disappears after that scene has finished. These seats are bolted to the deck. (01:25:50 - 01:35:25)
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: When Quint and Hooper show their scars and as Quint talks about the U.S.S. Indianapolis, the leftover food on the plate keeps changing between shots, as does the position of cutlery, etc. Hooper's position on the seat (note the window behind him) changes between shots as well. (01:28:00)
Continuity mistake: As Quint and Hooper drink to their legs, Brody lifts his sweater to see his own scar. Beside the portable stove, to Brody's left, there are four canned goods behind the green canisters of gas. Just after the shark starts to ram into the boat, there is a close-up of the stove, but now there are only two canned goods, a cup appears, and other changes in position, eg the liquor. (01:28:20)
Continuity mistake: When Hooper asks Quint about being on the Indianapolis, both of his shirt buttons are unfastened. When Quint answers & starts telling the Indianapolis story, Hooper's bottom button is fastened. (01:29:20)
Continuity mistake: There are two buttons on each of Quint's shirt cuffs. When Quint pokes his head out as he works in the engine room, one button is closed on his right cuff. When he gathers the rope in hands, just as the shark surprises him, he has two buttons closed, then as the rope is pulled from his hands only one button closed. (01:36:50)
Continuity mistake: When Quint is wearing the bandana round his head, the design showing and thickness of the bandana keeps changing in consecutive shots. (01:36:50)
Continuity mistake: When the barrel pops up at the stern of Orca, Hooper grabs the boat hook and reaches for the barrel. In the side shot the barrel faces Hooper's right and the homing device is at the top, in the back shot the homing device is gone and in the third front shot the barrel faces Hooper's left. (01:37:10)
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)
Continuity mistake: After Quint receives the rope burn on his hand, the shark creates a huge splash wetting Quint and Hooper. In the following shots the wetness of their clothes and hair varies greatly, particularly Quint. (01:38:00)
Continuity mistake: When Brody tries to hail the Coast Guard, Quint smashes the radio and the stove area beside them is visible. When the shark re-appears Quint heads for the stern, and the stove area, which is visible as he walks, is completely different. (01:38:25)
Continuity mistake: After Hooper says, "Oh boys, I think he's come back for his noon feeding," when Quint rushes to the pulpit one of the iron rail bars around the pulpit is bent, but in the following shots it is straight again. (01:39:15)
Continuity mistake: On the Orca near the end of the film, there is a shot of Quint aiming the harpoon gun. In this shot the harpoon gun is high, but in next shot he is shooting from the hip. (01:39:20)
Continuity mistake: After Quint trashes the CB radio, he runs to the pulpit with his harpoon gun. Between shots, he goes from leaning over the rail to standing inches away from it. (01:39:20)
Continuity mistake: Just after Hooper remarks, "Fast fish," as they chase the shark, there is a close-up of Brody leaning over the starboard side of the boat, beside the boat's wake. However, in the previous and following wideshots Brody is at the port side of the boat, as it speeds after the shark. Neither are flipped shots. (01:40:35)
Continuity mistake: The number of barrels on the deck of the Orca changes from shot to shot, during the final scenes at sea. (01:41:00)
Continuity mistake: During numerous close-ups on the bridge deck, such as when Brody is behind the wheel, as Hooper shouts, "Our injectors got scored from the salt water in the fuel," the three large gauges over the steering column are seen. The center gauge has a wide shiny chrome trim, and a partial black face with a silver center. However, in the extreme close-up of the gauge panel, it is an entirely different style RPM gauge, and it now has a blackish rusty trim, and a solid black face. (01:41:00)
Continuity mistake: After Brody throws down the pump, the shark causes the boat to tip. In the following close-up of Quint's hand, the black and red painted gauge panel behind the wheel is visible. The peeled paint, or lack of, on the ledge going round the bridge deck, and on the steering and throttle controls panel, differs greatly in most of the shots of the bridge deck. (01:41:05 - 01:46:40)
Continuity mistake: Aboard Orca, right beside the yellow barrels on deck, there is something large that is wrapped with green tarp and rope going round it. The tarp and the rope change significantly between consecutive shots throughout their hunt. (01:41:15)
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.