Factual error: The boat used by Bullock and Defoe to get off the cruise ship is water jet powered. The boat is shown launching from a dry dock and into the water using its engine. This is impossible. The only way for a water jet powered boat to accelerate is to be in the water.
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.
Continuity mistake: Just before the evacuation, the ship stops. When Merced runs to the computer in the bridge, the speed indicator shows 18.2 knots.
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.
Revealing mistake: In the very beginning of the film, when Alex rides his motorcycle to catch the bad guy, when he flies through the air you can his stunt double who has blonde curly hair. And when the camera goes to a close-up to Alex, you can see his hair is black.
Continuity mistake: When Alex rescues Drew, it is the middle of the night. There are a few consecutive events, then it is instantly daylight. But the events are all consecutive. There is no way the sun could rise that fast.
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 ★