The title is an allusion to "tapping" recruits into the secret society Skull & Bones, as well as into The CIA.
Filming was done all over New York City. Locations include Union Theological Seminary, Bronx Community College, Alder Manor, Fordham University, Brooklyn Historical Society, Church of the Intercession, and additional locations on Manhattan's Upper East Side, City Island, the Bronx, Brooklyn, and Yonkers.