This episode takes place in a mining community on May 21, 1910 and in Arizona in 1958 and 1968.
Lyn Murray was given an on-screen credit for "Music", but the bulk of this episode's score was made up of music previously used on Irwin Allen's Voyage to the Bottom of the Sea and Lost in Space, for which Murray had no composer credits.
Two actors in this episode named Paul (Paul Fix and Paul Carr) were also in the second pilot and third episode aired ("Where No Man Has Gone Before") for Star Trek. Fix played the chief medical officer, Dr. Piper; and Paul Carr played the part of Lee Kelso, helmsman, of the USS Enterprise. Neither character appeared again, as DeForest Kelley's Dr. McCoy replaced Dr. Piper, and Lee Kelso was killed by Gary Mitchell.