 The unit filmed at the Watergate Hotel and were staying there the night of the notorious break in.Despite a script which showed the CIA assassinating people and involved with various nefarious plots, Winner was given permission to shoot in the CIA Headquarters in Langley, Virginia.Scenes at Cross's home were actually filmed at then CIA Director Richard Helm's home in NW Washington D.C. Arnold Picker, Chairman of United Artists, was surprised that the CIA would allow such a thing and insisted that Winner show them a copy of the script before shooting began.