Stella and Clay name their baby Brian after Clay's friend Brian Armstrong (Jay Hayden) who died in Season 1, Episode 5 'Collapse' from a parachute malfunction during training.
The obscene details that Stella mentions in Ash's postcard is him saying that since he's been in the South Pacific he has "explored more virgin territory than Captain Cook and am giving Mount Orohena a run for its money as the highest point here". Captain James Cook (1728-1779) was a Royal Navy captain of the HMS Endeavor, he was an explorer and cartographer famous for being the first to map the area of the Pacific around Australia and New Zealand. Mount Orohena is located in Tahiti and is the tallest mountain in the French Polynesia with an elevation of 7,352 feet above sea level.
Captain Reyes is wearing the Surface Warfare insignia below his service ribbons, meaning he served on and was qualified to perform various duties aboard Navy surface warships; the Surface Warfare badge is awarded to commissioned officers who passed qualification and served as an officer of the deck, small boat officer, combat information center watch officer, and must be trained in shipboard engineering, naval history, and damage control. He is also wearing the Information Dominance Warfare Officer insignia above his ribbons, Information Warfare officers possess extensive skills in information, intelligence, counterintelligence, human-derived information, networks, space, and oceanographic disciplines in support of the Navy. Information Warfare is the job Davis does for Bravo, once she has been an officer for enough time to complete all the needed qualifications she will be awarded the Information Dominance Warfare Officer badge.
Clay and Stella were using a HelloBaby Baby Monitor.