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: 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: 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: When Alex and Dante are in the bow thruster room, Juliano is giving them instructions over the public address system. However, just as Alex is about to dive under the water to turn the wheel, Juliano tells him to "hold on" and starts giving him more instructions. There is no way he could have known that Alex was about to dive.
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.
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.
Answer: There is no logical reason for it and it is purely for cinematic theatrics. It's a movie myth that cars, boats, etc. immediately explode upon impact. In real life, explosions rarely happen that way.
raywest ★