Theodore Roosevelt did serve as New York City police commissioner for two years beginning in 1895.
St. Elizabeths Hospital was the site of a Federal Mental Asylum frequented by members of the armed services who were deemed unfit for duty. In the early twenty-first century, it is slated for redevelopment as the Headquarters of the Department of Homeland Security.
The full name of Luke Evans' character is John Schuyler Moore. Schuyler is an old New York Dutch family whose roots can be traced back to well before the founding of the nation and has close ties to the Roosevelt clan. A well-known ancestor of Moore was Elizabeth Schuyler, wife of Alexander Hamilton.
In the original novel, the character John Moore is a crime reporter. In the TV series, he is an illustrator. In one episode, Moore purchases a typewriter at a tricky tray event and tells Sarah Howard that he is interested in becoming a writer.
Blackwell's Island was later named Welfare Island, and subsequently renamed Roosevelt Island. Due to the number of hospitals and asylums, the area was designated as a Hospital Park. By the mid-twentieth century, it became a mixed-use zone, through the introduction of residential developments, and by the twenty-first century, a satellite campus of Cornell University and Franklin Roosevelt's Four Freedom Park was established at the Southern end of the Island.