The US Navy allowed the production team to film scenes aboard the Arleigh Burke-class destroyers USS Halsey and USS Dewey as well as the USS Iowa museum ship. The destroyers were sailed several days out to sea so that the cameras could shoot 360 degrees without having to worry about coastlines, buildings, and other ships appearing in the background. Many of the sailors in the background were the crews of those ships going about their duties as cameras rolled.
Even though Tom Chandler, the Commanding Officer of the Nathan-James, holds the rank of Commander, he is called Captain at times because of Naval tradition. That tradition is to call whoever is in command of a Naval vessel Captain, regardless of the actual rank they hold.
The Italian cruise ship in episode 1 is actually the retired Cunard White-Star Line RMS Queen Mary, a 1936 ocean liner-turned-hotel offering art deco decor, fine-dining & casual eateries, bars & a spa. She's permanently moored in the port of Long Beach, California and has been since 1967.
Coincidently, the actor that originally was cast as Lt. Kara Foster got pregnant, due to the pregnancy she was recast.
In the original 1988 book the Nathan James' hull number was DDG-80, which was assigned to the USS Roosevelt in 1999.
The gold anchor on the bow of the USS Nathan James is a Retention Excellence Award for crew re-enlistment.
In season 2 episode 11, there are scenes showing an offshore oil rig in the Gulf of Mexico off New Orleans. In several shots hills can be seen in the distance, something that is impossible in the waters off Louisiana.
The USS Halsey acts as the stand-in for the USS Nathan James for the most part. The ship's dog, on the show, is called Admiral Halsey.
Episode 6 of Season 2 is supposed to be located in Florida but was filmed in Long Beach, California. The school buses are California school district buses.
S2/E11 distant shots from the oil rig supposed to be off the coast of Louisiana show mountains higher than anything within 1000 miles of the region.