Dr. Thatcher, the scientist charged with weaponizing the Moon during the NASA Moon landings, is revealed to be a former member of a partisan organization known as M.A.D.: Mutually Assured Destruction. This designation, coupled with the fact that he seems to have lost his grip on reality in his old age, makes him - quite literally - a "M.A.D. scientist."
Dr. Thatcher's room number is 101, the same number as the room that contains "the worst thing in the world" in George Orwell's novel 1984. Eugenia's room number is 221, the same number as the Baker street address of Sir Arthur Conan Doyle's consulting detective Sherlock Holmes and Dr. Watson.(Holmes address is actually 221b)
The quote, "Last chance to be a hero, doc." by Jack Carter is the exact quote that the USS Voyager's computer said to the EMH during one of the EMH's daydreams in the Star Trek Voyager's S06E04 "Tinker, Tenor, Doctor, Spy.
When Carter come to see dr. Thatcher in his room, the latter is talking to himself and in front of him is a projection of a Castle. This castle is the Stockholm Palace (Stockholms slott) also called the Royal Palace (Kungliga slottet) of Stockholm in Sweden. Also seen in the picture is the top of the churchtower of Storkyrkan.