Oscar Homolka replaced Jack Hawkins in playing the character of General Golitsyn. The role had originally been intended for Hawkins, but his death in 1973 led to the part being re-cast with Homolka.
This movie was nominated for a BAFTA Award for Best Supporting Actress for Sylvia Syms, but lost out to Ingrid Bergman for Murder on the Orient Express (1974).
Dame Julie Andrews once said of this movie in mid 1973: "This is a nice film. It's just right for my comeback."
The old black-and-white espionage movie seen playing on the television was Sir Alfred Hitchcock's Foreign Correspondent (1940). Dame Julie Andrews worked with Sir Alfred on Torn Curtain (1966). That movie and this movie are cold war thrillers.