Factual error: Throughout the movie, everytime some type of casualty occurs or an alarm sounds, police type lights go off throughout the ship. Submarines don't have flashing lights or grated decks for that matter throughout the ship. The sound of the alarm is enough, since there are no deaf personnel on board a submarine.
Factual error: When the Captain (Gene Hackman) is getting ready to address the crew, the Chief of the Boat (an enlisted man) is briefly shown barking orders to the crew wearing a combination cover with an officer's golden chin strap. A Chief Petty Officer wears a black chin strap. Contrary to popular belief, it's not illegal to wear an accurate uniform on film, in fact the military offer their help to ensure uniforms are accurate: http://www.defenselink.mil/news/NewsArticle.aspx?ID=516, so that's not the reason.
Factual error: At one point, the US sub's starboard (right) side is shown to have an American flag painted on the hull near the bow. The flag's blue field is at top/left when on this side of any vehicle, it should be at top/right. Proper display of the flag requires the blue field always be located 'forward' of the remainder of the flag on all vehicles, be they plane, boat, tank or even space shuttle. (01:19:15)johnrosa
Factual error: After the 2nd sub attack, while Hunter is in charge, a call is made from conn to maneuvering, to restore propulsion as soon as possible. It shows a young black dude answering back on the MC, having to yell over the noise of water spraying everywhere. This was laughable. Maneuvering is the control room for the nuclear power plant. It's all control panels and 4 technicians plus the EOOW, a nuclear-trained officer or senior enlisted, who would be answering back to conn. There wouldn't be any flooding going on there. (01:09:45)leepster
Factual error: Upon the order to dive the boat when leaving port, many of the crew are shown hurrying around (especially up and down ladders). Everyone would already have a place to be on the maneuvering watch.