Just like Penny Robinson's complete absence in War of the Robots (1966) (until the trailer), Will Robinson similarly does not appear in this episode except in the trailer for next week's adventure; however, unlike Penny in War of the Robots, Will's name is mentioned (twice) as if he's somewhere around.
Michael J. Pollard plays the adolescent boy trapped forever in the mirror universe. Even though he was 26 years old, he still looked young enough to play a young teenager. Oddly enough, just a few months later he would be cast in a very similar role in Miri (1966), where he would once again play a trapped young adolescent unable to grow up.
The robot does not appear or receive mention anywhere in this episode (not even in the trailer).
Professor Robinson calls Debbie a he although Penny always calls her a she.
The title refers the communication device used in the fairytale Snow White and the Seven Dwarfs.