During filming, Karl Malden's London hotel room was burgled, and his cash was stolen, but his travellers' cheques were left untouched. The incident inspired him to become the spokesman for American Express travellers' cheques, in a long-running series of commercials, with the slogan "Don't leave home without them."
André De Toth originally was chosen by producer Harry Saltzman to direct this movie, but when De Toth broke his neck in a skiing accident, he recommended Ken Russell to replace him, based on the latter's creative television work. Russell was contractually obligated to direct this movie. He did not want to do it, but according to him, "It was shoved down my throat." De Toth reportedly did some direction, but refused to take credit on a movie signed by another.
There was controversy when this film was released in the United States, as it was felt to be too favorable towards the Soviets.