Other mistake: *Spoiler Alert* The strength of the underwater suits is wildly inconsistent. Rodrigo's suit almost immediately cracks and implodes, killing him. Paul's suit is easily ripped open by the creatures, also killing him, but Norah is repeatedly slammed into the sea floor by one of the creatures and her suit remains remarkably intact.
Suggested correction: It is stated by one of the survivors that one of the helmets was damaged. Rodrigo had the damaged one.
Actually, that's not completely accurate. She says something like "Faulty, I knew they were faulty." That also doesn't account for the fact that the creatures tore Paul right out of his suit, but couldn't seem to do the same with Norah.
His suit was faulty. He noticed a crack when he first picked it to put it on.