Part of the movie was filmed at Submarine Base New London, Connecticut. A few naval combatants rarely seen in Technicolor are visible in the early part of the film. The PT boats seen near the beginning are the 77-foot Elco type. The submarine primarily featured as "Corsair" was the experimental , with a conning tower modified to resemble her sister . A few O-class and R-class submarines, built in World War I and used for training in World War II, are visible in the background of some shots. For wartime security reasons, no submarine classes used in combat in World War II appear in the film. is seen in one shot; there are probably not many good Technicolor views of a four-stack destroyer available today. "Semmes" was being used as a sonar testbed at the time.