- If the worm-creatures are all part of one creature, why do they thrash around and fight each other for meals on occasion? Cephalopods have several "brains" across their main body and each tentacle. The limbs are mostly on auto-pilot.
- Why do the worms smash their way through doors before the galley scene and then start closing and even locking them to herd the characters afterwards? The tentacle that sneaks up behind Mulligan has to have come through the hatch Finnegan closed and locked, which means that the monster just figured out how to open the door locks, and is immediately putting that knowledge to use.
- During the climax, why does the creature hold Finnegan up to its eye rather than just swallow him with one of its tentacles? If it's anything like a normal cephalopod, then it's fairly intelligent and likely curious. Remember, the tentacles catch prey with touch and sound, so the creature probably wants to actually see the little things that have been causing it so much trouble.
- During the face-off with Mulligan, Finnegan tells an anecdote about an octopus that figured out how to open a bottle, reach inside, and eat the fish it contained in less than two minutes. Just under two minutes (real time) pass between Mulligan sealing the remaining door to the kitchen where they're hiding, and his realization that there's a tentacle right behind him.
- Those fairly likeable characters like Leila who died? They all died a slow, agonizing death.
- The text that appears on-screen at the very beginning says that the cause of all the South China Sea ship disappearances has never been revealed. It doesn't say "until now" or anything like it, which rather implies Finnegan, Joey and Trillian won't be getting off that island alive to tell their story.
- Why would anything that feeds on the body fluids of its prey have so many teeth? Biting into flesh with them would spill the very fluids being sought.
- The same reason a snake does. The creature swallows its prey whole, liquefies the flesh, then excretes the bones. The teeth help it gain a grip to swallow its victims.
- We see whale skeletons at the end, so presumably it has drained whales as its prey. The various fangs could be used to fight and kill such creatures, or to help hold onto larger prey while trying to devour it.
- Why did Trillian even try to rob the vault so early in the cruise ship's voyage? She didn't know anything about the plot to sabotage the vessel, let alone the monsters, so for all she knew she'd be stuck on board for days, hiding whatever she'd stolen as the ship was searched.
- She could've stole it and then left.
- Left the room, yes. Left the ship? Not likely, unless she was planning on drifting away in a lifeboat.
- If sabotage had already taken out the Argonautica's instruments, why was the sonar operator still able to detect the oncoming blip coming up from below, and call off how fast it was approaching? Even if the saboteur was worried that the cruise ship might collide with some uncharted shoal before Hanover's men arrived to loot the vessel, the rudder had been rendered inoperable, so leaving the sonar systems untouched by the sabotage couldn't help it avoid such a collision.