The title is a line from Shakespeare's Macbeth.
Guest star Joanna Barnes had had a recurring role on the series ''The Trials of O'Brien'' which had afforded Angela Lansbury one of her own rare television guest star gigs: however Barnes was evidently not featured in the relevant episode (Leave It to Me (1965)). Lansbury and Barnes are connected via Lansbury's headlining the Broadway musical ''Mame'' and Barnes being afforded one of best remembered roles (as Gloria) in Auntie Mame (1958) the filmation of the stage musical ''Mame'''s source play.