In every shot from above the water of the party ship the rear paddle wheel is stopped. But when the shark is attacking the ship from below, the paddle wheel is turning.
When Ryan first gets in contact with Max Burns he states that he needs help and they are coming from the Persephone Research Station.He mentions the station is gone and a lot of people are dead. Max tells him to slow down and asks: " What do you mean 'attacked'?. Ryan never mentions the research center was attacked, until after Max says it.
In all of the overhead or panning shots of the party there are no people on the deck. However, in a couple of overhead shots there are a couple of people at the front of the top deck.
After the lab is destroyed, two survivors swim to the environmentalists' boat. After getting it started, one guy says that he cannot get the boat closer to shore because he is afraid of grounding it. But in the very next scene, we see the shark swimming below the boat in what looks like about 80 feet of water.
When the shark attacks the party barge and it starts to rock you can see clearly the folding tables with plastic cups of drink on them and chairs next to them not moving or being knocked over by the shark rocking the boat or the people running past them.
People on a boat spot an island where they want to land. It is covered with trees. After cutting away, the island is again shown. This time it is almost barren.
When the survivors are jumping off the boat to escape to the party island, you can see someone sitting in the driver's area of the boat.
During the tour of the underwater facility, it is stated that there are 2 underwater docks and 3 submarine vehicles. But for a lab complex this large, they don't have an above ground dock to bring in personnel and supplies.