Efrem Zimbalist Jr. decided to grow a big, bushy mustache to distinguish himself as the villain in the film, but director Robert Day talked him into shaving before the cameras rolled.
This was a proposed pilot for an ongoing Witch Mountain TV series.
Eddie Albert is the only original cast member from the first "Escape to Witch Mountain (1975)" movie to return for this installment. All the other roles were recast with new actors/actresses.
Costars Eddie Albert and Efrem Zimbalist Jr. both acted opposite Audrey Hepburn, Albert in Roman Holiday (1953) while Zimbalist did in Wait Until Dark (1967).