Continuity mistake: When Denzel Washington meets Gene Hackman for the first time, Hackman is holding a cigar in front of his mouth. In the next shot, his arm is suddenly down on the table, and he lifts the cigar to his mouth again. (00:06:30)
Continuity mistake: When the fat sailor gets on the bus, Dougherty is adjusting his hat with his left hand. In the very next shot he has his right hand on his hat. (00:11:45)
Revealing mistake: When the men are waiting at the dock and when boarding the submarine, we see the wide shot of the submarine and the dock. The ocean is, however, incredibly calm despite there being torrential rain happening throughout the scene on the dock. While it's not seen, this would be from a rain machine not able to cover the entire location of the shot. (00:13:51 - 00:16:38)
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. (00:15:41)
Audio problem: When up on the top of the submarine, Ramsey says, "Hunter?" and Hunter replies, "Sir"; however, his mouth doesn't move. (00:17:00)
Continuity mistake: In the scene where the "Alabama" dives, what we see isn't a ballistic missile-carrying submarine (SSBN), but an attack sub (SSN); actually more than just one, since the masts and periscopes keep going up and down in different shots. It seems that the navy wasn't too willing to cooperate in the production of a film depicting a mutiny onboard a nuclear sub, so the shots were "stolen" from a helicopter in the vicinity of some navy base. (00:18:00)
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. (00:18:30)
Factual error: You don't wear your working uniforms underway. You all have coveralls on, both officers and enlisted. (00:18:30)
Continuity mistake: As the Alabama dives for the first time you will notice that the periscope and antennae masts protruding from her conning tower keep switching from up to down, indicating that the film crew used footage from two different sub dives to achieve that sequence. (00:18:50)
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. (00:23:10)
Factual error: Several times during the movie, we can see the radio operator with the screen contents "printed" on his face. As everyone knows, that just doesn't happen in real life. (00:25:00)
Character mistake: More than once the crew of the submarine salute the Captain while uncovered in the hallways of the sub. Sailors never salute without their cover on. (00:29:10)
Character mistake: When Denzel is talking to the crew about upgrading to DEFCON 3, they say the last time was 32 1/2 years ago during the Cuban missile crisis of October 1962. The problem is that they both take place during October, meaning that the half year part is a mistake. (00:34:00)
Continuity mistake: The captain says to make torpedo tubes 1 and 4 fully ready. When they're fired, they use torpedo tubes 2 and 4. (00:46:15)
Factual error: Throughout the movie, all sorts of messages are passed over the 1MC (ship's intercom) when the boat is supposed to be stealthy. They've set "Ultra Quiet" to avoid the enemy sub but no-one was any quieter, and everyone was still using the 1MC. Worse, people are shouting commands and status updates, both in person, and over the intercom! No wonder that Akula found them. The only thing protecting this ship was plot armor! In real life, messages would be passed quietly using sound powered phones (which we also see), rather than blasting the info loudly to the entire crew, because sonar will literally pick up the sounds of loudspeakers and people shouting. Let's not even mention classified target data being passed to the entire ship's crew on the 1MC. (00:49:00)
Continuity mistake: When discussing the broken EAM, Hunter is holding the message with two hands or one hand depending on the angle. (00:53:50)
Continuity mistake: When the incomplete second EAM is shown in the movie for the first time, its subject line states "nuclear missile launc..." However, when this same message is finally received at the end of the movie the subject line states: "terminate launch all missiles". If the first one had been consistent with the second this would have made quite a difference. (00:55:45 - 01:45:25)
Continuity mistake: When Hunter is arguing with the captain, he is listing off points and raises his thumb and forefinger in points 1 and 2. When the shot changes, he has a closed fist. (00:57:00)
Factual error: Many times the Captain is wearing a red baseball style cap. This is only worn by the Captain when drill is underway to signify, "I'm here, but not really here for the purpose of the exercise." (00:58:20)
Suggested correction: Coveralls did not become the primary uniform underway until the NWU Type I was found to melt, which was post 2010. Prior to that, enlisted wore the blue two piece working uniform, and officers and chiefs wore khakis.
Not true. I'm a veteran of 10 ssbn patrols during the 80s and 90s. Everyone wore coveralls, and that included all ranks up to and including the captain. However, coveralls weren't required. My second captain always wore khakis. We wore them because they were more comfortable and functional than dungarees and khakis.