Continuity mistake: When Hooper gets his gear from below, after the explosion in the engine room, he runs to the deck passing Quint using the fire extinguisher. The camera pans from Brody, who stands on the bridge deck, to Hooper right below him. So where exactly is the tall iron ladder that leads up to the bridge deck in this shot? It should be behind Hooper, in front of the window, but it's gone. Don't fret, it's back in the following shots.
Visible crew/equipment: When the fishermen start out on the hunt, Ben Gardner appears in a close-up leaning on the windshield at forward deck, while talking about how stupid some of the others are. In the next wide shot of the boats, Ben's green boat is towards the left of the screen, and the large reflector screen and camera, that are mounted to the bow of his boat, are visible in front of the forward window where Ben is seen in the previous shot.
Continuity mistake: At the scene just after the fake shark scare, the real shark shows up at the pond area of the beach. As the lifeguard in a small boat reacts to everyone's panic, the shark tips over the boat then appears underneath him to tear his leg off. We watch as it sinks slowly to the bottom. You can plainly see that the lifeguard is barefoot in the boat. The severed leg has a tennis shoe on.
Continuity mistake: Quint embeds his machete into the wood at the side of the boat, but in the following wideshot the machete is gone. Then as Orca starts to move, when Hooper says, "He's chasing us, I don't believe it," the machete is back. But when the shark leaps onto the boat the machete is gone again, and then as the shark devours Quint the machete is back for him to grab, so he can valiantly stab the shark.
Continuity mistake: The number of barrels on the deck of the Orca changes from shot to shot, during the final scenes at sea.
Other mistake: On the death certificate for Chrissie, the shark's first victim, the date of death is July 1st. But later, on the reward paper posted by the boy's mother, it says that the date of Alex's death was June 29th. Alex died after Chrissie, not before. Also, the form refers to the coroner as the "corner."
Revealing mistake: Just as Quint finishes scraping his nails on the chalkboard, the camera begins to move in closer when he takes the first bite of the cracker. On the right side of the screen under Harry's chin, Roy Scheider is seen ducking down while staring at the camera, as it pans toward Robert Shaw, and he then lifts his left hand up, cueing Robert's line.
Continuity mistake: When Quint goes below deck to get the machete, with the intent to cut the barrel lines, the machete he takes is shiny and clean, with no rust or pit marks at all. Yet, when Quint holds it over his head and then embeds it into the side of the boat, the entire blade is rusty and full of pit marks.
Continuity mistake: Quint slams the machete into the wood beside the side cleat, and rigging lines. However, when the shark joins them aboard the boat and Quint is sliding towards its mouth, the machete's position changes - it is farther down towards the stern, note the black anti-slip mats.
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.
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.
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.
Continuity mistake: When Brody is throwing chum in water and Quint is in the chair they show him wearing no socks and old tennis shoes. After Brody falls and then sets a new chum marker Quint has brown socks on and loafer type shoes.
Continuity mistake: At Orca's bow, the hole in the steel hull beside its number, is oval shape. However, after Quint is gone, when the ship begins to sink, and later when Hooper surfaces beside the wreckage of the bow, the shape of the hole in the steel hull is completely different! The white water stain lines change throughout the shots as well.
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.
Continuity mistake: At Quint's, when he holds the two steaming shark jaws, assorted dry goods on the shelves above the stove are seen, particularly the cans of Del Monte vegetables. When Quint gives Hooper the rope to tie the knot, some of the goods on the bottom shelf and every can of veggies on the top shelf are entirely different.
Continuity mistake: When Brody waits to board the ferry he says, "Charlie, take me over to those kids, will ya," and on the base of the ferry 'Amity' is written in large, bold, black letters. However, when they reach the other ferry landing the word 'Amity' is gone. It is the same side of the ferry, note the ferry driver and the back end of the car.