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)
Revealing mistake: When Brody tries to hail the Coast Guard, just as Quint smashes the radio, the reflection in the center window is of the three windows on the opposite side of the cabin. Though the two side windows being reflected are normal, the entire center window being reflected is blacked out, reason being that the camera filming this shot is positioned in front of that window and in order not to see the outline of the camera, the center window directly behind it was covered. In the previous and following shots obviously there is nothing blocking that window. Similarly, this occurs when Quint speaks with the Coast Guard. (01:38:25)
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)
Visible crew/equipment: After Quint smashes up the radio, the shark re-appears. In the shot of Quint, as he walks along the side of the boat, the clear reflection of the filming crew's vessel is visible in the nearest window. (01:39:10)
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)
Visible crew/equipment: In the scene where Quint shoots the shark with a harpoon gun, when the harpoon hits the shark you can see the shadow of the cameraman. (01:39:25)
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)
Continuity mistake: There are long poles and large hooks clipped to both the starboard and port side of Orca. In quite a few shots all three poles are gone from either side, and in other shots the amount of poles and hooks and their positions change repeatedly over and over again, in consecutive shots throughout their hunt! (01:41:15)
Continuity mistake: The knots on the supporting rigging lines aboard Orca keep changing in consecutive shots, within the same scenes. (01:41:20 - 01:43:20)
Visible crew/equipment: Just after the two barrels pop up, Hooper comes down from the bridge deck and quips, "Now what?" In the next shot as the two barrels bob up and down, Orca is in the distance with Quint still up on the bridge deck, and Hooper and Brody standing on deck at the stern, but we can see there's someone else aboard who's moving around inside the cabin, beside the hanging net. (01:41:50)
Visible crew/equipment: Hooper and Brody grab a couple of poles as the Orca pulls alongside the two floating barrels. When Quint says, "Watch those barrels, boys. Watch them," the crew's vessel is clearly reflected in the cabin's side glass window. (01:42:15)
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.