The scene in which the U.S.S. Alabama is diving for the first time is footage of the real submarine submerging. Tony Scott was following along in a helicopter and a separate camera unit on boats obtaining shots of the ship. When the Captain of the Alabama requested that the helicopter cease filming, they submerged, which is what director Tony Scott was hoping for anyway.
Since the U.S. Navy would not cooperate with the filming, for several scenes the French Navy allowed the use of one of their Triomphant Class ballistic missile submarines along with the aircraft carrier Foch.
The refusal of an executive officer to agree in launching nuclear weapons due to a fragment order is based on a similar incident within the Soviet Navy. During the Cuban Missile Crisis, the Soviet submarine B-59 attempted to infiltrate the US Navy blockade by running submerged. By doing so they had been out of contact for several days with Moscow at the depth they ran at. When US destroyers dropped signal depth charges to force the sub to surface, the Soviet captain, Valentin Grigorievitch Savitsky, believed war had broken out between the US and the Soviet Union. His sentiments were concurred by the on board political officer, Ivan Semonovich Maslennikov. However, Savitsky's second-in-command, Vasily Arkipov, who also was the flotilla commodore, refused. All three needed to agree before launching. Being out of contact for so long and with no clear orders, Arkipov convinced Captain Savitsky to surface and they found themselves surrounded by US destroyers. Their communication was reestablished with Moscow and they received orders to return home, thereby preventing nuclear war.
The U.S. Navy found the subject of the film objectionable and inaccurate. It refused to provide any assistance in the movie's making.
Tony Scott obtained footage of the real USS Alabama departing Pearl Harbor through possibly illegal means. A paid civilian informant tipped off Scott to the day and time of Alabama's sortie from port, an obvious violation of navy ship movement regulations. Scott then had camera boats and a helicopter on standby to film the surfaced sub. Reportedly, the Alabama's captain requested assistance to remove the film crew but then simply decided to submerge the sub prematurely, footage Scott was hoping to obtain anyway. Although the Navy issued a formal protest about using its equipment in the film without permission, it was not illegal as the sub was in public view, and they could do nothing to prevent it. Interestingly, Scott was hoping only to obtain footage of an Ohio class sub in motion on the surface, the fact that the boat was the actual USS Alabama was sheer coincidence.