Gert Fröbe plays a man called "Steinhäger". In Germany Steinhäger is a alcoholic drink with a minimum of 38% ABV and is distilled in Steinhagen.
During the fake interrogation of Eddie Chapman in London, he is asked what film he saw in the movie theater. He answers; "Warsaw Concerto" with Anton Walbrook and Sally Gray." This could be an inside joke and reference to the film Suicide Squadron (1941) with participation of the mentioned actors and written by this film's director Terence Young.
The United Artists soundtrack album was arranged and conducted by Roland Shaw, but he did not work on the film's original score.
Original Bond director Terence Young wanted his Dr. No (1962) leading lady Ursula Andress to star opposite Christopher Plummer.
Terence Young, the director, knew Eddie Chapman from before the Second World War, and had met Chapman during his first "mission" to the UK.