The original title for this series was "Please Stand By," but because the Cuban Missile Crisis had happened less than a year earlier, executives thought it might make people fearful of an air raid. As a reference to this, when Au-delà du réel - l'aventure continue (1995) would cut to a commercial, the Control Voice said, "Please stand by."
The first season finale, The Forms of Things Unknown (1964) (starring David McCallum, Vera Miles, Cedric Hardwicke, and Barbara Rush), was supposed to be a pilot that series creator Joseph Stefano presented to network executives. When it was rejected, he used it as an episode of this series.
Many scenes and some entire episodes of the series were filmed on-location at series creator Joseph Stefano's house, called "Villa Di Stefano," from which the production company took its name.
Dominic Frontiere and Robert Van Eps scored the first season of this series. Frontiere composed new music, as well as re-used his music from previous television shows, such as Stoney Burke (1962). The second season was scored by Harry Lubin, who also composed new music, and re-used his music from previous television shows, such as One Step Beyond (1959).
When the series finale, The Probe (1965), was originally aired on January 16, 1965, a live announcer spoke over the Control Voice's closing statement about returning "next week at this same time." The live announcer stated that The King Family Show (1965) would be seen "next week in this time period." The regular Control Voice closing for The Probe (1965) was heard only in re-runs.