Continuity mistake: When the divers are positioning the cord on the rocks, in the opening shots, in one shot there is a tall seaweed plant, fully erect, floating around. In the next shot the plant is down in half, positioned totally different. (00:01:15)
Continuity mistake: At the beginning of the movie, when the divers find the Orca boat, there is a plate with the word "ORCA", nailed to the front of the boat. However in the first movie this wasn't here. Also, the damage done to the Orca is noticeably different. (00:02:00)
Continuity mistake: When the divers find the Orca, one diver goes through a door still latched to the frame, in perfect condition. But seconds later the other diver takes a photo of this diver in front of the same door, which is now hanging off it's hinges and is damaged. (00:02:05)
Visible crew/equipment: When Brody drives across the deck and then onto the ferry, as he does you can see the large shadow of crewmembers and a camera set up, standing on a high ledge above, cast on Brody's Amity Police van. (00:03:20)
Continuity mistake: At the beginning of the film when Brody parks his van, the position of the parked van changes. In the first shot his front door is parallel with the front door of the van's next to his. In the next shot, Brody's van is now parked much further back. (00:04:50)
Continuity mistake: When Brody arrives at the Grand Opening Ball he start fixing his tie and his upper shirt button goes up. When it cuts it's buttoned. (00:05:35)
Continuity mistake: When Tina is called forth to cut the ribbon, she walks up and stands a few feet in front of the girl in the yellow dress. When it cuts, they have moved closer to each other. (00:06:10)
Continuity mistake: When Tina walks to cut the ribbon, her Miss Amity sash changes position between shots. (00:06:20)
Continuity mistake: When Tina cuts the ribbon, the way she holds the scissors in changes between shots. (00:06:50)
Continuity mistake: When Mike says Sean can't come with him, Tina says, "He can help me, at least" with her hair hanging over her right shoulder. When it cuts, her hair is pulled back. (00:12:10)
Continuity mistake: When Hendricks enters Chief Brody's office with the diver's camera, the camera is old and a very dark brown. The middle circular lens has an inside light bulb-fitting and the large black torch attached to it is worn and slightly damaged. However, in the shots of Hendricks saying "Dance?", he is holding the same camera but it is clearly different. The camera is lighter in color, the inside light bulb-fitting from the middle circular lens has vanished, and the black torch is newer-looking. (00:15:10)
Continuity mistake: When a group of teenagers are aboard a boat, hauling the boy back and forth on the bungee swing, between shots the positions/locations of the teenagers changes. (00:16:00)
Continuity mistake: When a group of teenagers are aboard a boat, hauling the boy back and forth on the bungee swing, between shots a bunch of boats and catamarans which are drifting on the water behind them, suddenly vanish. (00:16:35)
Continuity mistake: When Terry is water-skiing, the sky keeps alternating from cloudy to sunny and back, and the roughness of the waters she skies on changes as well. (00:17:45)
Continuity mistake: When Tina and Eddie are making out, just before Tina hears the sound of Terry water-skiing, the position of Eddie's guitar, radio, blanket etc., changes between shots. (00:18:00)
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: 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 Brody walks up on the old lady's porch and Tina says "We heard this noise like a boom", Brody has his hands hanging down. When it cuts, he has them up. (00:22:40)
Continuity mistake: When Hendricks pulls the thick power line out of the water, the position of the seaweed and plant life hanging from the line changes and decreases depending on the shot. Also, the way in which the white claws are inserted into the power line change too. (00:24:45)
Continuity mistake: When Ellen grabs the coffee pot from the stove she grabs the handle with her right hand and place the left hand on the side of the pot. When it cuts her left hand is down. (00:25:00)
Answer: For what it's worth, in the novelization the shark is a female and pregnant with the offspring of the first movie's shark, but that's not brought up in the film at all.