The original Broadway production of "Five Finger Exercise" by Peter Shaffer opened at the Music Box Theater in New York on Dec. 2, 1959, and ran for 337 performances.
When Rosalind Russell is in a record store, there is a record cover behind her--it's for it's "Auntie Mame".
When Philip says he is reading the play Elektra, Louise says, "I saw it in San Francisco. I'll never forget that wonderful scene where they put out his eyes." Though nobody corrects her, the audience is supposed to understand that Louise is foolish and pretentious. The famous scene in which the hero is blinded is in the play Oedipus Rex.
Alec Guinness and Trevor Howard were sought for the role that eventually went to Jack Hawkins. Laurence Harvey was originally announced for the role eventually played by Maximilian Schell.
In 1962 Rosalind Russell appeared in movies with both Natalie Wood (Gypsy) and this one with her sister Lana Wood.