Wissenswertes

Donald Pleasence came up with the idea for his character to constantly use a hankie.

The amount of the ransom money in the source novel was $500,000. But in this movie, the ransom was represented in the form of high-grade uncut diamonds, worth £517,057.

In his memoirs, Joss Ackland wrote that he was working on three other movies, as well as playing Wray in this movie.

The first movie that director Don Siegel shot in Europe.

The marquee of the theater, in which Tarrant and his wife have their appointment, advertises "Die Luftschlacht um England (1969)," which also starred Michael Caine.