This is actually based on two Donald Hamilton novels - the one with the same title and also the first in the Matt Helm series, "Death Of A Citizen". From this novel comes the introductory business of Matt Helm returning reluctantly to the world of espionage through the intercession of a woman named Tina. However, it must be stressed that there is very little of either book in this film - the Matt Helm novels are very serious and view the world of espionage coldly as something very unpleasant, whereas the films are ridiculous parodies done in imitation of the James Bond series.
Although one of the greatest female dancers in the history of the movie musical, Cyd Charisse singing in films was almost always dubbed. A young Vikki Carr performed her singing in The Silencers (1966).
The gorgeous statuesque blond stripper in the opening title sequence is dancer Larri Thomas who would later portray Henrietta Hippo on TV's New Zoo Revue in the early 1970s.
In the scene where Matt Helm (Dean Martin) is checking into the Phoenix Hotel and Andreyev (Roger C. Carmel) is lurking in the foreground, the hotel newsstand is immediately behind him. The newsstand shelf is lined with books from Donald Hamilton's Matt Helm series, on which the movie is based.
A Frank Sinatra song (Come Fly With Me) has a cameo in this movie series. It would be followed in The Ambushers (1967) by another Sinatra song - Strangers In the Night. Both songs were always played before or after Dean Martin's song Everybody Loves Somebody Sometime whenever Matt Helm is trying to set a romantic mood with a girl. Also, on both occasions, Martin made fun of those songs (calling Sinatra "terrible" in this movie, and in The Ambushers referring to it as a Perry Como song).