It took me so long to figure out the twist that wasn't a twist at all I felt embarrassed. Let's put it this way -- the "It's A Disaster!" trailer has a mistake in it, but an easily understandable one.

Ooooh, I haven't seen the film, but I *think* I might know what the twist is.

Is it that the Yay! Spaceships! are actually Yay! Actual Ships? As in they float on top of the rising waves, thus leading to salvation and a clunky Noah's Ark analogy?