Deadliest of the Species - S3-E11
Other mistake: When the Robot is returning to his beloved with the energizer, he gets near the right side of the shot and abruptly vanishes rather than rolling off camera normally.
Lost in Space (1965)
1 other mistake in season 3 - chronological order
Starring: Guy Williams, June Lockhart, Mark Goddard, Marta Kristen
Other mistake: When Don and Dr Smith are stealing Sesmar's control unit, look closely at the base of the electronic arch - Raddion is hidden from sight but the careful eye will see his golden feet.
Dr. Smith: Oh, the pain, the pain.
The Great Vegetable Rebellion - S3-E23
Trivia: Due to their uncontrollable laughter during filming of the infamous "Vegetable Rebellion" episode, Guy Williams and June Lockhart were written out of the next two episodes.