 FACT: While investigating San Francisco through the periscope, the  Captain incorrectly addresses Swain as "Mr. Swain". Usually only  Officers that are Lieutenants or lower (like LT Garcia) are  addressed as "Mr. ...." (i.e. Mr. Garcia). Enlisted men are usually  addressed by their rate (i.e. Sonarman Swain, STS2 Swain, Petty  Officer Swain, etc.).