This is the only episode that Billy Mumy didn't appear in. That wasn't good. Between that and Dr Smith's ineffectual light colored top, the episode started off on a bad note. What was even worse was the show's worst guest star: Michael J Pollard. On my most recent viewing, I realized that the story is a little better than I had originally thought. The beginning, when Prof Robinson and Major West assume that Dr Smith had installed the "storm arresters" is genuinely funny. West says: "It's a good thing, we had Smith install the arresters." West said this as if he really believed what he was saying! The main part of the story, which concerns Penny finding a "magic mirror," is OK, but compromised by the wrong actor. The character referred to as "the boy" was played by Michael J Pollard, who was at least 26 years old at the time. Pollard was twice as old as Angela Cartwright. Despite this, the episode played as though Penny and "the boy" were supposed to be the same age. In addition to being too old for the part, Pollard's performance was completely generic. Overall, the episode is watchable, but could have been much better. Pollard was a bad choice.