There is a female chief petty officer (the one performing CPR at the beginning of the episode) shown wearing a Navy SEAL "Budweiser" badge. As of the episode's air date, no woman has successfully begun, much less completed, Navy SEAL (BUD/S) training. Hence there are (currently) no female SEALs in the US Navy.
Over and over the submarine is referred to as a "nuclear sub" implying that it has nuclear weapons on board. The phrase "nuclear sub" is used to indicate a submarine that is nuclear powered. A submarine that carries nuclear weapons should be referred to as a "ballistic missile submarine."
Kasie says the counter lung is an oxygen tank. It is not, the counterlung is the part of the breathing loop in a rebreather that mixes the exhaled air with fresh oxygen and scrubbed CO2.
The USS Memphis was Decommissioned April 1 2011.
When Gibbs and Bishop are locked in the DC repair locker and Gibbs says a torch would get them out. DC lockers have PECU's (Portable Exothermic Cutting Unit) for just that purpose.
After the sub dives, Ellie says she "just tried our sat phone". This would be a violation of the radio silence order, albeit the transmission would be minimal as the sub is effectively a Faraday cage. All devices capable of transmission would be turned off.
The "Weapons Officer" on a US Navy Submarine is always a Commission Officer, not an enlisted First Class Petty Officer a shown.
Kasie says the diaphragm on the gas check valve was removed leading to the SEAL's death. Ellie says it was the Over pressure valve that caused the problem. They are different parts.