Factual error: When Ryan is brought on board the Dallas, Captain Mancuso climbs down from the conning tower, through the hatch next to the control room of the sub. He then walks/runs down two flights of stairs and enters a short corridor where Ryan is now dropped on the floor by the safety diver and another crewman. I am unsure of the exact location of the lower hatch of the escape trunk on a 688 sub, but I suspect it would be on mid deck. When the camera turns to face Mancuso again you see the curvature of the hull next to him, suggesting this takes place on an upper floor on the sub. So why did he run down two stairs to seconds later end up on the top floor of a sub with only three floors inside the pressure hull?
Factual error: When the USS Dallas submerges to attack the Red October, they rig for battle stations as well as rig for red. On a submarine, rig for red is only for periscope depth operations at night, to allow control room watchstanders eyes to adjust to the darkness topside. No other area on the boat rigs for red. Throughout the movie the lights darken along with battle stations. No naval ship would reduce visibility on purpose in a heightened state. (01:31:00)
Trivia: Paramount Studios essentially rented a US submarine to be in the movie. The USS Houston (SSN 713) played the USS Dallas and the surface scenes were filmed off of Long Beach, CA and Port Angelas, WA. Two crewmembers off the Houston were actually given very small speaking parts in the movie.