Many shipboard scenes were filmed on the WWII aircraft carrier USS Yorktown (CV-10), a museum ship moored in Charleston, SC. Aircraft on display on the flight deck served as some of the aircraft seen in the movie. The Yorktown is not a "supercarrier," as the USS Polaris is depicted to be, so there are noticeable differences between the ship as seen on deck and the wide shots of the ship seen at sea, the most obvious being the island superstructure.
The New York City streets were actually various streets in downtown Wilmington, NC, with NYC landmarks like the Empire State Building added in the background in post-production.
Onboard scenes were filmed on the USS Yorktown which is permanently moored in the Charleston , S.C. harbor. The ships number "10" is clearly visible in several scenes.
Shipboard scenes were filmed on the Battleship USS North Carolina, permanently moored in Wilmington, NC
The US Navy has very strict standards for Navy personnel's weight relative to their height, known as Body Composition Standards. These standards are part of the Navy's Physical Readiness Program. The goal of the program is to ensure serving enlisted and line officers have the fitness to perform their duties. The Captain is clearly overweight and if he was not able to meet meet the minimum weight standards within an a reasonable pwriod of time, he would likely have to resign his Commission.