Other mistake: Alex jumps from the deck to the stern and falls into the sea. The ship moves at a speed of about 15 knots, and there is no chance that in a few seconds Alex could climb back to the ship, because he would be at least 50 feet away. (01:26:55)
Other mistake: At the end when the plane hits the tanker, people shout "abandon ship" and next shot, a lifeboat full of people is halfway down the side of the ship. This would be impossible. (01:48:00)
Other mistake: Throughout the entire film, Alex manages to keep the engagement ring in his pocket after everything that happened. (01:51:50)
Suggested correction: People manage to keep things in their pockets all the time after enduring a lot of different activities. This is in no way a mistake whatsoever.
Other mistake: While the ship rips through the town, many buildings seems to get smashed. But in the shot from above not all the damaged buildings are visible. (01:41:10 - 01:45:00)
Other mistake: In more than one scene, Alex is normally talking to Drew although she's deaf. She wasn't looking at him while he was talking, so she couldn't have read his lips.
Other mistake: The bow thruster is activated to avoid colliding with the oil tanker. Since the thruster is never turned off, the cruise ship should have continued on traveling in circles. However, after scraping the oil tanker the cruise ship travels in a straight line into the island.