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: During numerous close-ups on the bridge deck, such as when Brody is behind the wheel, as Hooper shouts, "Our injectors got scored from the salt water in the fuel," the three large gauges over the steering column are seen. The center gauge has a wide shiny chrome trim, and a partial black face with a silver center. However, in the extreme close-up of the gauge panel, it is an entirely different style RPM gauge, and it now has a blackish rusty trim, and a solid black face. (01:41:00)
Revealing mistake: Towards the end of the movie, when Quint is practically bitten in half, the mechanical shark's rubber teeth bend as it bites down, and they also bend when the shark bites down on the tank. (01:57:10 - 01:58:05)
Revealing mistake: When Brody tries to hail the Coast Guard, just as Quint smashes the radio, the reflection in the center window is of the three windows on the opposite side of the cabin. Though the two side windows being reflected are normal, the entire center window being reflected is blacked out, reason being that the camera filming this shot is positioned in front of that window and in order not to see the outline of the camera, the center window directly behind it was covered. In the previous and following shots obviously there is nothing blocking that window. Similarly, this occurs when Quint speaks with the Coast Guard. (01:38:25)
Continuity mistake: When the shark is boarding the boat, Quint and Brody are on their backs in the cabin beside the table. It is clearly visible that they are lying on the very solid floor with the hatches in perfect condition, despite the visibly massive damage to the floor and hatch when the engine room exploded. (01:57:00)
Visible crew/equipment: After Quint smashes up the radio, the shark reappears. In the shot of Quint, as he walks along the side of the boat, the clear reflection of the filming crew's vessel is visible in the nearest window. (01:39:10)
Continuity mistake: Just as the first cleat flies off the stern of Orca, the shape of the small metal hood differs and the entire wood rail at the top of the transom in this close-up differs from the rail in all other shots. The long wood rail has another small piece of wood attached at the end, forming an 'L' shape with a 90° angle, whereas in all other shots the rail is one long solitary piece. (01:44:55)
Continuity mistake: When Chrissie goes swimming at the start of the film, we see the moon in the distance. However, when we see Chrissie from the shark's point of view under the water, the moon is directly above Chrissie.
Visible crew/equipment: After tying off the cleats, the shark pulls Orca causing it to tip. As Hooper and Brody fall backwards onto the deck, in this close-up the white tape mark is visible on the black anti-slip mat - where Quint will land the machete in a subsequent shot. (01:43:00)
Continuity mistake: When Hooper asks Quint about being on the Indianapolis, both of his shirt buttons are unfastened. When Quint answers & starts telling the Indianapolis story, Hooper's bottom button is fastened. (01:29:20)
Continuity mistake: In the famously later on added scene Ben Gardner's suddenly emerging head scares the hell out of Hooper the diver (as well as any viewer). What diminishes the effect is that the second close-up of the head looks nothing like the first, much creepier one.
Audio problem: While Chrissie is being attacked at the start of the film, when her mouth is visible it is not in sync with her screams. (00:04:15)
Visible crew/equipment: Aboard the Orca, Brody accidentally causes the cage bars to fall over, and as both air tanks roll forward the multiple head set lights are reflected on the two tanks. (01:13:35)
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. (01:25:00 - 02:01:10)
Revealing mistake: When the bottom half of Quint's body is in the shark's mouth, Quint's fake belly shifts around where the shirt is open and the edge is also noticeable under his shirt. (01:57:25)
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. (01:07:00)
Continuity mistake: When Brody fires the last shot at the air tank, in the next close-up of the shark, the tank lies parallel to its body deep within its mouth, with only the base of the tank visible between its teeth. However, in the next wide shot, the tank lies perpendicularly in its mouth, with the pressure knobs at its right. (02:00:10)
Continuity mistake: During the shark's attack on Orca, the tall, large steam pipe clamped to the wall, beside the bridge deck ladder, actually differs from the steam pipe seen in previous shots. (01:49:55)
Visible crew/equipment: Hooper and Brody grab a couple of poles as the Orca pulls alongside the two floating barrels. When Quint says, "Watch those barrels, boys. Watch them," the crew's vessel is clearly reflected in the cabin's side glass window. (01:42:15)
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)
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.