Continuity mistake: After Brody walks out of the store with a box of sign supplies, wood stakes, and boards, Brody dumps everything into Hendricks' arms, with the points of the five wood stakes facing Hendricks' right side. When Brody drives away as Mayor Vaughn calls out to him, Hendricks walks over with his arms full, but all the stake points now face his left and the supplies box is turned around, note its printed sides. (00:11:15)
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: Throughout the film, there are abrupt changes concerning the position of the sun's shadow, or going from being windy to not, or being overcast to bright and sunny, or where the water is either at a dead calm or pretty rough, all between consecutive shots within a scene. (00:15:15 - 01:21:30)
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: Near the end, when Quint is struggling to get away from the shark, the nearby cans on the deck change between shots.
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: When Hooper runs below deck to get the electronic homing device, in the wideshot he breaks apart the plastic case, throwing the clear top to one side and the yellow bottom to the other side. However in the next close-up the plastic case is suddenly intact, right below Hooper's hands. The yellow cord is in Hooper's hand in the wideshots, but not in the close-up. (01:23:55)
Continuity mistake: While Brody and Hooper are at Quint's, just as Quint says, "And don't forget the color TV," the six small shark jaws hanging on the far wall, beside the window to Brody's left, are visible. However, when Hooper ties the sheepshank knot, there are only three small shark jaws beside that same window, near the stove. (01:06:30)
Continuity mistake: When Quint and co. are tracking the shark, they use harpoons tied to barrels to tire the shark. When the shark is approaching Brody, who sits on the foremast waiting to shoot it, the surface of the water is visible behind it and the barrels are gone in two shots. The barrels are also gone when the shark blows up. (01:59:40)
Continuity mistake: On the dock, as the Tiger shark is being raised there is an arrow above its gills, a second arrow below its dorsal fin and a broken arrow shaft in the wound just beside that dorsal fin. When Hooper tells the three fishermen that it's a Tiger shark, the broken arrow beside its dorsal fin is now a nice, long, whole arrow. All of the arrows change their degree of penetration in the shark's hide throughout these shots. (00:32:55 - 00:34:20)
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: 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)
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: When the shark swims away with the roast bait, a dramatic close-up of the quickly unfurling thick link chain lying on the dock is shown beside the trashcan. The unmoving end of the chain lies behind, to the left of the trashcan and the end being pulled is on the right, with the slack at the center. Now when the chain is pulled taught in the following shots, the trashcan should have flipped over, if the slack chain was indeed where it was shown to be in the close-up. In the wide shots the trashcan sits on the left at the center of the dock, but the chain being pulled is attached to the piling at the right corner end of the dock. (00:26:15)
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: At Quint's place, he lifts two shark jaws out of the boiling water on the stove, in the close-up. In the next wideshot, the two jaws are positioned differently within the tongs Quint holds. (01:06:55)
Continuity mistake: When Brody boards the Orca, as Quint shouts, "Daylights wasting," the other docked boats along the surrounding shoreline are visible; for example, right across the docked Orca is a yellow boat pinning a white boat between it and the shore. When Orca gets underway, the yellow boat now pins a red boat between it and the shore, and in the close-up of Brody at the stern, there is a small white boat to his left that disappears in the next wideshot. (01:11:40)
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: In one of Richard Dreyfus' first scenes, Brody asks him to help with the group of men crowding into a small boat. Hooper says that the officer wants him to tell them that they're overcrowding the boat. They show the men climbing in and there's a guy in a blue jacket climbing down the ladder into the boat. He waves his arm and says "what do you care?" They then show Hooper asking if they know a good restaurant or hotel on the island. When they show the men again, uttering the line "Yeah, walk straight ahead," the man in the blue jacket is on the deck again and is again descending down the ladder. (00:29:00)
Continuity mistake: On the Fourth of July, Sean (the youngest Brody kid) is wearing a white t-shirt with orange around the collar, and green shorts. But after Michael goes into shock and Sean is seen crying, he's suddenly wearing darker shorts and a plain white shirt with no orange. Later at the hospital, he has his orange and white shirt and green shorts on again. (01:01:55)
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.