Continuity mistake: When Brody thinks he spots a shark, he rings his bell, then begins to descend the watch tower. In one shot you can see a woman with blonde hair, sitting on a beach-chair, at the bottom of the watch-tower. In the next overhead shot, as Brody runs across the beach, the same woman now suddenly has an orange hat on. (00:44:50)
Continuity mistake: When the kids are drifting around, a heavy rain shower comes. Seconds later, in the shot of Sean on the upside-down sail boat, you see reflections of sunlight and a large part of the boat he is sitting on is completely dry.
Continuity mistake: When Tina cuts the ribbon, the way she holds the scissors in changes between shots. (00:06:50)
Continuity mistake: When the shark is attacking the catamarans with the teenagers aboard, in one shot you see Andy fall backwards, still on the catamaran, and he is barefoot. He is then knocked in the water, and when his friends pull him back out of the water on, he now has white trainers on. (01:20:10 - 01:21:15)
Continuity mistake: When Brody and his wife are driving towards the harbour just after the diving accident, the sky is overcast. When they get to the harbour the skies are clear. When they sail away in the police boat the sky is overcast again.
Continuity mistake: When Tina is running away from Eddie in the building on the beach, you see that the building is casting a huge shadow across the beach. But when it cuts to the next shot in which they are running past all their friends, there is no shadow being cast on the shore from the building. (00:26:35)
Continuity mistake: After Tina yells that the shark is still there, we see her placing her hand on Ellen's shoulder. When it cuts to Brody getting off the sailboat Tina has her hand on Ellen's hip. (01:18:20)
Continuity mistake: In the scene when Chief Brody, his wife & deputy come across the sail boat named "Tina's Joy", they find Tina in it, and during this scene Chief Brody's jacket is placed on Tina's shoulders. The Chief then leaves the sailboat in search of the other teens. Later scenes show the Chief wearing this jacket when in fact he left it with Tina.
Continuity mistake: At the end of the movie when the Chief has killed the shark, you see his son Shawn cheering, with his hair completely wet and messed. By the time the Chief paddles over, Shawn's hair is now perfect; dry, and combed neatly...
Continuity mistake: When Brody is at Phil's to develop the pictures we see in an overhead shot Phil picking up a Polaroid sheet and on his side there is a pincer. When it cuts the pincer has changed position. (00:48:55)
Continuity mistake: When Brody is out looking for the kids, and he sees Mike's boat approach - the sky in the background is overcast. When they meet, the sky is clear.
Continuity mistake: When Bligh is pumping the patch up on his inflatable boat, when it shows a close-up of it, there are empty black hooks underneath it. Yet when the patch bursts, there is now white rope running through the previously empty hooks. (01:19:25)
Continuity mistake: When Bligh is in his boat, pumping it up with his foot, he changes from using his right foot, to his left foot and back to his right foot between shots. (01:19:15)
Continuity mistake: In the close-up scenes at Cable Junction, with water, the sky is clear. But in the scene where Brody is climbing on to the cable, the sky in the background is completely gray - and actually looks like a studio wall.
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)
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 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)
Continuity mistake: When Mike and Sean are on the boat and Mike says "If you're gonna get in the way you can just go home" and Sean grabs the line with one hand. When it cuts, he's holding onto the line with both hands. (01:00:35)
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 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)
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.