Bud states that Master Chief Morris is deployed to the USS Patrick Henry, like most ships mentioned in JAG it is fictional. There has only been one vessel in the US Navy with that name, and that was the USS Patrick Henry (SSBN-559), a George Washington-class ballistic missile submarine. Named after Revolutionary War hero and founding father Patrick Henry she was laid down May 27, 1958, launched September 22, 1959 and commissioned on April 11, 1960, the Patrick Henry and her sister boat USS George Washington were the Navy's first missile submarines. Over her tenure as a ballistic missile submarine the Patrick Henry completed a total of 22 nuclear deterrent patrols in the Atlantic Ocean. After the Strategic Arms Limitation Treaty (SALT) of 1979 reduced the number of missile boats in service the Patrick Henry and her sister ships were converted into heavy attack submarines in 1982 to make room for the then new Ohio-class missile submarines, the Patrick Henry was recommissioned as SSN-599. However due to their size they did not make effective attack submarines, as such the Patrick Henry only served as an attack submarine for two years before being decommissioned in May of 1984, along with her sister boats, with their crews being transferred to newly constructed Flight II VLS equipped Los Angeles-class fast attack submarines.
Bud states that he isn't sure if they have probable cause to detain or talk to William Hawkings, as he is just sitting in his car. Ignoring the fact that JAG officers do not have law enforcement authority (especially over civilians), there certainly is plenty of probable cause to detain Hawkings. As a registered sex offender it is a violation of his parole and/or conditions of release for him to be within 1,000 feet of a school or any place children frequent. He is parked right next to a school watching children, if they had called the DC police Hawkings could have been placed under arrest for this violation, which would give them leverage over him.
The character William Randall Hawkins is played by Vyto Ruginis, who also plays Arkady Kolchek in NCIS: Los Angeles, a spinoff of NCIS which is a spinoff of JAG.