Continuity mistake: Brodie is racing in his vehicle down the beach to investigate an incident, driving to our left. He then gets out of the car and is shown running down the beach to the left. Unfortunately, the scene was shot with Brodie running to the right. The editor simply reversed the film so Brodie would be running the right direction. You can see backwards writing for about 2 seconds.
Continuity mistake: After Chief Brody is fired from his job, he comes home drunk. No beer cans can be seen spilling out of his car or on the ground. The next day when he is taking his wife to work, there are several empty beer cans on the ground. Where'd they come from?
Continuity mistake: Chief Brody and his raft disappear from under the shark when it catches fire. Understandable, as they were burning the model shark for real, but still poorly edited.
Revealing mistake: When Chief Brody sees the driftwood in the water, he sits down and takes his shoes off to wade in. As he sits down, his butt is already wet, even though he sits in dry sand.
Factual error: Brody would have also received a shock inside his raft due to proximity and water continuity.
Continuity mistake: In the beginning of the movie when Terry is water skiing, the boat has a 70hp 3 cylinder Johnson. When the shark is eating the boat it's a 1977 55 horsepower motor that still has the 70hp decal on it.
Continuity mistake: Brody has a hold of the large power line, and the shark is gliding along straight for it. In all the shots of Brody holding the power line, the green jacket he wears has wet splashes on it. One patch of water on his right shoulder briefly disappears for one shot, the reappears in the following. (01:46:45)