Character mistake: When Quint is telling the story of the Indianapolis, he says the ship went down on June 29th. It actually went down at 12:14 a.m. on July 30. (01:32:45)
Continuity mistake: When Quint is telling Brody and Hooper about his body loses during the past, he pulls out a partial denture. In the final scene on the Orca, Quint is shown without this denture, but when he is being eaten by the shark and screams in pain, his teeth are complete again. (01:56:20 - 01:57:20)
Continuity mistake: At the beach party, when Cassidy and Chrissie make eyes at each other, in the close-up he sits behind certain people including a girl with blond braids and guy in a denim shirt, with long sleeves. However, in the next wide shot, denim shirt guy has his sleeves rolled up and many of their positions are different. (00:02:00)
Revealing mistake: During Chrissie's attack, she clings to the buoy and cries, "Oh my God! Oh God!" In the next shot, as she is pulled away from the buoy, a wire (at about the height of the bell) that shimmers in the moonlight and bounces up and down with the buoy, runs from the buoy towards the right of the screen. It is not visible in any other shot. (00:04:35)
Continuity mistake: When Hooper climbs into the cage he is not wearing fins, yet when he is lowered in the cage, in the very first shot underwater, he is wearing fins. In the following shots he is not wearing fins, but after the shark destroys the cage and he swims to the bottom of the ocean, he is wearing fins once again. (01:52:40)
Visible crew/equipment: After Brody buys the sign supplies, when Hendricks shows up Brody places the box in the front seat, and as Hendricks tells Brody about the Boy Scouts, pay attention to the left window across the street, where we can see one of the local residents holding a camera and looking out the window facing the location shoot, taking pictures of the actors and film crew. The filming took place at the corner of Main St and S. Water St, Edgartown. (00:10:50)
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: 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: When Hooper is lowered into the water in the shark cage, in the following shots the ring he is wearing on his left hand vanishes and reappears in a few shots, such as when he drops the poison shark dart. (01:53:50)
Visible crew/equipment: After Quint walks on deck and tosses the life vests to Hooper and Brody, Quint asks, "Hooper, what exactly can you do with these things of yours?" Just as Hooper turns around, the clear moving reflection of a boom mic and pole are visible on the glass of the door to the cabin, just behind him. (01:50:15)
Continuity mistake: After Hooper pulls the tooth from the hull of the boat, in the shot just as Ben first pops out, the knife Hooper holds has a protective sheath on the blade, yet in the previous and following shots the pointy serrated blade is not covered. (00:49:30)
Continuity mistake: When Brody sits on the beach watching the crowd in the water before Alex is killed by the shark, he wears a watch on his wrist which disappears a few shots later when he believes he saw something. (00:14:48)
Continuity mistake: There is a scene where Chief Brody and his wife are talking about their son's birthday present. She says that he probably won't go in the water after what happened yesterday (the attack on the Kintner boy). The next day is when the shark is caught and Hooper makes a comment about the shark's digestive system being very slow and anything he's eaten within the last 24 hours would probably still be in there. From the earlier scene it would make it 48 hours since the Kintner boy was killed. (00:35:20)
Continuity mistake: When Chief Brody asks, "How many guys you gonna put on that boat?" he stands between two adjacent pilings. Hooper then stands beside the same two pilings in the following wide shots. However, in the close-up when Hooper asks about a good restaurant on the island, he is at the center of the shot standing beside only one lone piling. Richard Dreyfus' beard is also fuller in the close-up, than in the wide shots. (00:28:50)
Continuity mistake: As the shark pulls on the lines tied to the stern cleats, the boat tips to the side and in the wide shot the emblem on one of the air tanks faces the side. but in the next close-up as they hit the ladder, both face front. (01:43:05)
Revealing mistake: While Hooper is below in the cage, he sees the shark nearing and up on deck as the barrels speed closer, the black triangular device attached to their lines is clearly visible, right in front of the barrels. The device pulls the barrels, not the shark. (01:53:15)
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)
Visible crew/equipment: Just after the shark's first surprise attack on Hooper's cage, bright blue equipment is visible just past the cage, as the shark swims away. (01:54:10)
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: When Mayor Vaughn, Hendricks and the others join Brody on the ferry, as they reach the other side of the harbor the coroner's front leans on the car, as he faces the Mayor and Brody. However, in the next shot the coroner's back now leans on the car, as he faces the opposite way. (00:13:25)
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.