Plot hole: Dafoe and Bullock leave the ship a long time before it hits the tanker and there is a lot more time before it crashes into the town and even more before Alex gets on that speedboat. No matter how fast he could have gone, there is no way he would have caught up with them.
Plot hole: When Drew first went into the elevator, Geiger's clock on the countdown for evacuation said 5 minutes about. When Drew gets stuck in the elevator when Geiger blows up the charges he positioned throughout the ship, the countdown on the computer had stopped already. How could Drew be in the elevator for five minutes, if not longer? It wouldn't take 5 minutes to get up a couple of floors.
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 ★