This was Cedric Hardwicke's final television acting role before his death on August 6, 1964 at the age of 71.
The episode was actually a pilot for a proposed series to be called "The Unknown." When it was rejected by ABC, producer Joseph Stefano used it for the final episode of the first season of this series; however, the pilot The Unknown (1964) later aired separately on May 4, 1964. It was partly reshot to de-emphasize the fantasy elements.
The intense refrain of music heard several times in the episode was later used in The Invaders (1967).
The title comes from "A Midsummer Night's Dream," Act V, Scene i, where Theseus is speaking to Hippolyta: "The poet's eye, in a fine frenzy rolling, /Doth glance from heaven to earth, from earth to heaven; /And, as imagination bodies forth /The forms of things unknown, the poet's pen /Turns them to shapes, and gives to airy nothing /A local habitation and a name." Theseus' following words are the very words Tone says to Leonora when they first meet: "Such tricks hath strong imagination, / That if it would but apprehend some joy, / It comprehends some bringer of that joy. / Or in the night, imagining some fear, / How easy is a bush supposed a bear!"
David McCallum (Tone Hobart) later played Joshua Hayward in Feasibility Study (1997) while Barbara Rush (Leonora Edmond) later played Barbara Matheson in The Balance of Nature (1998). The only other actors to appear in both The Outer Limits (1963) and The Outer Limits (1995) are Leonard Nimoy, Cliff Robertson and Peter Breck.