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 the Tiger shark is displayed on the docks, the blood stains in and around the mouth and its body, either change significantly between shots or completely disappear. (00:33:00)
Continuity mistake: When Hooper measures the Tiger shark's mouth, the people standing around him change between the close-up and the previous and following wideshots. (00:33:30)
Continuity mistake: In the scene where Hooper is measuring the bite radius of the Tiger shark, he puts his measuring tape away more than once. (00:33:30)
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: Hooper wears rimless eyeglasses, with the arms either attached at the upper corners of the lenses or at the sides of the lenses. If this didn't happen between shots within the same scenes, it could be presumed that Hooper has two different pairs of glasses and switches between the two, but they do indeed change between shots, such as when Mrs. Kintner slaps Brody, or even later, on the Orca. (00:36:05)
Continuity mistake: When Mrs. Kintner confronts Chief Brody on the dock, in the shots facing her the veil blows away from her face, but in the shots facing Brody, the veil blows towards her face. (00:36:10)
Continuity mistake: When Sean mimics his father, Brody's glasses are lying upright on the table. However, when Hooper sits down the glasses are upside down and other things on the table change position, etc. (00:38:10 - 00:39:50)
Continuity mistake: At his home, after Brody uncorks the bottle of wine he begins to peel the top label. In the following shots the top label changes, as well as the position of his hands, depending on camera angle as Hooper and Brody speak. (00:42:45)
Continuity mistake: When Hooper cuts open the shark and empties the contents, the amount and position of the fish changes between shots. (00:44:00)
Continuity mistake: When Hooper is gutting the Tiger shark, the order of things he pulls out does not match the order that they land at Brody's feet, as Hooper throws them towards him, and some things just appear at Brody's feet. (00:44:05)
Continuity mistake: After Hooper cuts open the Tiger shark, when he throws a license plate towards the Chief the area to Brody's left is clear, but in the shot facing Brody there are lines and equipment lying on the ground beside him, to his left. (00:44:10)
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 Hooper pulls the tooth from the hull of Ben Gardner's boat, he wears his watch and ring on his left wrist and hand. However, in the close-up as he drops the flashlight, knife and tooth, he wears them on his right side. Flipped shot. (00:49:35)
Continuity mistake: As the Mayor walks over to the couple on the beach, to persuade them to go into the water, the back of the woman's lounge chair is visible. In the following shot from behind, as they stand up, suddenly a yellow towel is leaning over the back of her chair. (00:56:05)
Continuity mistake: When the 'shark fin' (boys playing a trick) approaches a woman she shouts, "My God!" and turns to swim towards the family with three children on a yellow raft, surrounded by other swimmers. In the next shot of a man's reaction, he too swims towards the very same family, but this time the children are in different order and no others surround them. (00:59:10)
Continuity mistake: When the man swims away from the 'shark fin' towards the family, in the shot from behind he swims between the older girl and young boy. However, in the next shot facing him he swims between the older and younger girls, causing the raft to tip. (00:59:10)
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)
Continuity mistake: When the shark enters the Estuary, he passes Sean playing on the sand. After the attack Michael is pulled ashore and there is a close-up of Sean crying. Behind Sean the orange and white stripe cabanas are visible. However, there are no cabanas at the shores of the pond; these cabanas are located at the main beach area. The footage of Sean, with the cabanas behind him, is from the earlier scene of Alex's attack. (01:02:00 - 01:03:30)
Continuity mistake: When Michael and his two friends are sitting in their boat, in the pond, in the first close-up they sit on the white wrinkled up sail, but in the next wideshot two of them sit on the spread out blue tarp. (01:02:00)
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.