Revealing mistake: After Terry has been taken by the shark, her mum stops the speedboat, and starts calling for her. Then the shark starts swimming over to the boat. In a following side shot of the boat, just before the shark slams itself into the speedboats side, you can see a thick line attached to the front of the speedboat, which wasn't there previously, which is probably used to tow the boat to something off screen. (00:21:10)
Continuity mistake: When Chief Brody comes home drunk, he finds Ellen and Hendricks sitting talking and he then comes in and pours himself and Hendricks a drink, in order to celebrate the fact that Brody has just given Hendricks his Chief of Police badge. Back and forth between shots, the amount of drink in Brody's glass differs. (00:56:05)
Continuity mistake: When Mike is repainting a striped beach-house, he turns to see his friends riding a catamaran, and he then turns and makes a big splodge with his brush on the second stripe from the side, on the beach-house. In this shot note the shape of the paint on this stripe. After Chief Brody rings the bell because he thinks he sees a shark, he begins to climb down the watch tower, and it then cuts to a shot of Mike standing in front of the beach-house - and now the shape of the paint-marks are different - they are lower and smaller. (00:42:35 - 00:44:50)
Continuity mistake: When Terry is water-skiing, her mum is driving the speedboat. The speedboat has the writing "MS 5713 EB" on both of its sides. The sides of the boat are made up of shiplap boarding. In the first half of the skiing scene when we see the side of the speedboat, the writing is printed on the second board down from the top of the boat. However in the second half of the scene, after Terry has been grabbed by the shark, the writing has moved up onto the top board. The condition of the paint of the actual whole boat changes between a few shots too. Sometimes the green paint is totally fresh and new looking, in others it is faded and looks more worn. (00:18:40 - 00:20:25)
Revealing mistake: During the scene in the bar, the first shot shows some kid playing an arcade of some sort, and the shot continues to scroll from right to left. However, all the writing (ie. the arcade machine, t-shirts, chalkboard, and various signs) are all backwards, which means the shot is flipped.
Continuity mistake: At the beginning of the film when the shark attacks the divers, you see in one shot that the shark already had a burned scarred face. The shark doesn't get set alight until later in in the film. This scene was one of the last ones to be filmed.
Continuity mistake: When Hendricks enters Chief Brody's office with the diver's camera, the camera is old and very darkish brown, and the middle circular lens has an inside lightbulb-fitting, and the large black torch attached to it is worn and slightly damaged. Yet in the shots of Hendricks saying "Dance?," he is holding the same camera, you can clearly see it is different. The camera is more lighter in colour, the inside lightbulb-fitting from the the middle circular lens has vanished, the black torch is more new-looking etc., (00:15:10)