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)
Continuity mistake: When the guy is standing on the beach in the opening scenes the sunset is covered by cloud. When seeing the sunset from the woman in the sea's perspective the sky is clear with no clouds. (00:02:50)
Continuity mistake: Check out the scene where the girl gets attacked at the start - keep your eye on the clouds and how they move around. (00:03:10)
Continuity mistake: In his bedroom, when Chief Brody asks, "How come the sun didn't used to shine in here?" the ashtray and lamp are visible beside Ellen. In the following shots the ashtray and lamp's electrical cord noticeably keep changing positions. When he walks out of the bedroom, something (mug?) appears on the desk near the window that wasn't there in the previous shot. (00:05:20)
Continuity mistake: When Michael walks into the kitchen, he holds up his bloody hand and exclaims, "I got hit by a vampire!" In the next wide shot the blood on his raised palm differs. (00:06:00)
Continuity mistake: When Brody questions Tom about Chrissie's disappearance, Brody turns his head away from Tom between frames, just as they hear Hendricks' whistle. (00:08:00)
Continuity mistake: After buying the sign supplies, Brody drives away and as the Mayor calls out to Brody, Hendricks walks over. In the first shot certain people are walking about; however, in the next shot as Hendricks and the Mayor speak, a boy suddenly appears standing in the crosswalk, the positions of signs, etc., differ, and of course the shadows cast are entirely different. (00:11:15)
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: When Brody waits to board the ferry he says, "Charlie, take me over to those kids, will ya," and there's a painted board with 'Amity' attached to the ferry base. However, when they reach the other ferry landing the board with 'Amity' is gone, in sloshing water (even more visible in a deleted scene). It's the same side of the ferry, note the ferry Captain stationed at the permanent helm at only one side. The short haul Chappy Ferry's On Time scow was the stand-in for the fictitious Amity ferry. (00:11:40)
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)
Continuity mistake: Before Alex's attack, the guy who plays with his dog Pippet on the beach wears a bright yellow Izod polo shirt with straight hemmed sleeves, in all of his close-ups. However, in all of the wideshots the polo he wears is pale yellow, with shorter sleeves that have the classic rib-knit sleeve openings. (00:14:10)
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: While Brody watches the woman in the water, before Alex is attacked, there is a blue and yellow raft in the cabana behind him. In the close-up of his face, just before Harry's black capped head pops out of the water, the raft is gone. Then when Ellen massages Brody's neck the raft is back. The cooler and other assorted items change position between shots as well. (00:15:00)
Continuity mistake: The position of the people while they sit or lie on the beach, before Alex is attacked, changes back and forth between shots throughout this scene. (00:15:10)
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: As Brody sits on the shore with Ellen, a councilman approaches. Between shots, Brody's left hand changes position - jumping from his lap to the back of the beach chair in an instant. (00:15:15)
Continuity mistake: When Ellen speaks with Brody at the beach, while worrying about the shark, Michael and other kids get up, and head toward the water. In the next shot, Michael, who wears very distinctive green and orange swimming trunks, jumps into the water (holding a football), and gets his hair and body entirely soaked. Next three shots Harry (and his 'bad hat') sits down and speaks with Brody. In the next shot Michael, with dry hair, passes Mrs. Kintner and is still running towards the water with Sean. (00:15:40)
Continuity mistake: The man speaking to Brody on the beach, while Brody is preoccupied with staring at the water, has salt and pepper colored hair, but in the close-up shots facing Brody the man's hair very noticeably differs, as well as his upper body structure and tan. (00:15:40)
Continuity mistake: Just before the Kintner boy is attacked, when Chief Brody is sitting on the beach watching the water, he speaks with the old man called Harry. In the close-up shot of Harry the chin strap of his rubber cap hangs down loose at his chest, but in the side shots the chin strap is tucked up at his ear (seen when Harry stands up). (00:16:00)
Continuity mistake: Before Alex Kintner is attacked, Sean Brody is shown sitting on the beach singing. After Alex is attacked and people are running out of the water, Sean can be seen standing on the beach, and in one shot, Chief Brody can be seen grabbing him. But a couple of seconds later, Sean is shown sitting on the beach in the same spot he was before, as if he hadn't moved. (00:16:55)
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.