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).
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.
Aside from being Martin's first appearance as Matt Helm, his only Billboard Hot 100 number 1 single during the 60's "Everybody Loves Somebody Sometime" also made its first cameo in this series (being played on Helm's car).
A Frank Sinatra song (Come Fly With Me) had a cameo in this movie series. It would be followed in the movie The Ambushers 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, in both occasions, Martin made fun of those songs(calling in this movie the first song disgusting and referring the second song as a Perry Como song in The Ambushers).