The worst error concerned the bow thruster at the end.
- Why was it still running? Almost all other electrical power was out, and a bow thruster would not be on an emergency circuit.
- When Richard Dreyfuss opens the hatch into the bow thruster shaft, a hurricane force of wind blows into the room. Ship propellers are slow-turning compared to aircraft propellers (so as to avoid cavitation) and are not going to move large quantities of air - hardly any, in fact, as they're not shaped to move low density air.
- There seemed to be a propeller on either side of the shaft. For air to blow inward, both props would have to be pulling air towards each other. The idea in a bow thruster is to pull water in one end and out the other.
- Nobody would build an inward-opening hatch below the waterline.
Also, it seemed that from the ballast tank (by definition and appearance at the bottom of the ship) they seemed to travel UP a few levels, thus in reality placing them above the bottom of the ship.
I found it a bit hard to believe the Captain could have convinced anyone to stay in an underwater room with giant windows showing the ocean behind the glass.