Factual error: The "hard suits" the divers wear have soft, relatively normal gloves and soft joints. More akin to a football uniform with armor over spandex. They are at the bottom of the Mariana Trench, at 36,0000 feet below sea level. The pressure is over 7,000 psi. Without a hard suit, they would instantly be crushed.
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.
Other mistake: The station's escape pods are not too big but surely big enough for 2 slim woman - a possible weight limitation is out of question as well. They could easily use it together and survive, so Norah's self-sacrifice makes no sense at all. Besides, what if all 6 crew members make it to the pod hub? Rock, paper, scissors?
Factual error: The way the implosions were simulated isn't exactly accurate. At that depth, going from a pressurized suit immediately to unpressurized would completely crush you, to almost non existence. Instead, in the cases of Rodrigo and the captain, they seem to explode with such a force (an outward exertion of energy) that it blows everything and everyone back. The worst being Rodrigo, he "implodes" (as the movie says) but a regular sized (albeit torn off) human hand hits Norah on her helmet and I think there was a normal sized eyeball that floated by. Again, these parts would be reduced (or flattened) to an unidentifiable size.
Continuity mistake: In the opening shot as Norah is brushing her teeth, in one shot she pulls the toothbrush out of her mouth, the next shot the toothbrush is in her left hand as she grabs a paper towel, the next shot you see both empty hands as she uses the paper towel to scoop up a spider, then the next shot has the toothbrush back in her mouth without a transition of her putting it back in her mouth. Then as she puts the spider down outside of the sync, the toothbrush switches sides of her mouth immediately in the next two shots.
Continuity mistake: They travel without their helmets but when they are about to go underwater they magically appear.
Other mistake: The Kepler's energy core is a huge nuclear reactor. It can easily obliterate the whole station so its accessibility should be protected by all kinds of fail-safe systems and high level security protocols, yet, Norah - a simple mechanic - can fire it up and overcharge it without any password, keycard, identification method or such, only by pressing a few buttons, then 'space' (not even 'enter'). There is not even a confirmation process before switching the reactor to terminal overload.