Continuity mistake: The zinc oxide on Brody's nose either appears or disappears between shots. When Brody pulls the wrong line causing the air tanks to roll, he falls back and there's zinc oxide on his nose, yet when he puts another chum marker in the water the zinc oxide is gone. Another example; when Brody says, "I can go slow ahead. Come on down and chum some of this sh*t," in a close-up there is no zinc oxide on his nose, yet when Quint remarks that it's a twenty five footer, suddenly he has zinc oxide on his nose. The amount of zinc oxide also changes between shots, when he wears it. (01:13:05 - 01:20:00)
Continuity mistake: In the first scene of the Orca at sea, Hooper holds a green tackle box as Quint cracks open a beer. The way Hooper holds the tackle box varies between shots. (01:13:05)
Continuity mistake: When Quint drinks the beer then crushes the can, the sea behind him is all choppy. When Hooper crushes the plastic cup, the sea behind him is virtually calm. (01:13:15)
Continuity mistake: When Quint finishes off his beer and squeezes the can with his hand, Hooper's equipment is visible just behind Quint. Then Brody accidentally unties the cage bars. When he falls back into Hooper's equipment, now it is closer to the door and the lines securing them are entirely different. (01:13:25)
Visible crew/equipment: Aboard the Orca, Brody accidentally causes the cage bars to fall over, and as both air tanks roll forward the multiple head set lights are reflected on the two tanks. (01:13:35)
Continuity mistake: As the tanks of compressed air roll towards Hooper, the large silver cage canisters near the ladder are visible. When Hooper carries a tank to the cabin saying, "You screw around with these tanks and they're gonna blow up," there is a long grey cloth (scarf?) lying on one of the canisters. (01:13:40)
Continuity mistake: On the Orca, after Brody's first attempt at a sheepshank, his hands grip the rope a couple of feet apart from one another. Between shots, his hands instantly come back together. (01:14:25)
Visible crew/equipment: When Quint hears the clicking fishing reel, he puts on the harness and slowly lifts the rod. At the start of the shot facing the reel, a crew member's hand and the top of his head are reflected in the circular chrome. (01:15:25)
Continuity mistake: When Quint slowly clips his harness to the fishing reel, the reel has a brushed chrome dull finish. However, in the previous and following shots, although the reel style is the same, the reel has a highly polished mirrored chrome finish. (01:15:25)
Continuity mistake: When the fishing reel clicks, Quint readies himself in his chair and Brody is finally successful with the knot. The knot in the rope, and the way he holds it, differs between the close-up and wideshot. (01:15:50)
Continuity mistake: Orca's ID number normally reads MS 15 LF on both her port and starboard side at the bow. However, after Quint shouts, "Hooper, you idiot. Ain't you watchin it?" Orca's ID number reads M 15 L at starboard side and 15 LF at port. (01:16:30)
Continuity mistake: When Quint shouts for Hooper and Brody to get their gloves on, in the wideshot Hooper starts to slip his left hand into his left glove. However, in the close-up, he just starts to put his right hand into the right glove. (01:17:40)
Continuity mistake: The cleats are entirely different in many shots; they keeps changing from flat top, long, shiny silver with a wide base, to curved top, dull silver with a narrow base. When Brody unties the wrong line and when he wets the fishing reel it is the shiny flat top cleat on the transom. Yet, when he and Hooper tie off the lines the cleats are curved top. Also, the two metal plates and two metal hoods that are near the cleats repeatedly change from being very rusty, to not rusty at all. (01:17:40 - 01:22:00)
Continuity mistake: Just as Quint shouts, "You may be a big yahoo in the lab, but out here you're just supercargo..." and when he asks Brody to unbuckle him, the cleat at the stern has plenty of line wound round it and there is a red cup beside it. However, in the previous and following consecutive shots within this scene, there is no line and no cup. (01:17:50)
Continuity mistake: The fire extinguisher in the cabin, between the door and window, changes from an older tank to a clean newer one. Note the label and condition of red tank when Hooper sticks his tongue out at Quint and later when Quint removes it to put out the fire in the engine room. The silver clasp holding the tank reverses itself and the black holder changes its position on the wall between shots as well. (01:19:30 - 01:48:00)
Continuity mistake: While Brody and Quint are talking in the cabin, just after Hooper sticks his tongue out at Quint, the books on the shelf are fallen over on their sides. However, in the next shot when Quint walks out on deck, the books are visible behind him and now they're upright. (01:19:45)
Continuity mistake: When Brody starts chumming, the stern of the Orca is bloody and the white container is dirty and bloody. When he and Quint watch the shark coming towards them, the container is much cleaner and the pattern of blood on the boat, at the stern, differs. (01:20:45)
Continuity mistake: While Brody starts to chum, Quint goes to the cabin to sit and work on the fishing reel, and the portable stove is visible to his right. Then when Quint speaks with Amity Point light station the pots, kettle, etc., on the stovetop are positioned differently and now there is an additional white pot. The hanging net has fewer things too. (01:20:50)
Continuity mistake: Chief Brody has a cigarette dangling from his lips as he famously tells Quint, "You're gonna need a bigger boat." In the overhead shot as the shark passes the stern, just below Quint, Brody flicks his cigarette towards the left of the screen. However, when Hooper leaps down the ladder Brody's cigarette is back in his mouth. (01:21:20)
Continuity mistake: After Brody says, "You're gonna need a bigger boat." he and Quint go out on deck and there is a long rope tying the open cabin door to the rigging at the rail. However, when Hooper jumps down from the bridge deck the rope is gone. (01:21:25)
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.