Revealing mistake: When Will looks through a window of the prison spaceship they crash landed on, a prisoner's hand moves on the staff he's holding, but he is supposed to be frozen and unable to move. (00:32:10)
Lost in Space (1965)
1 revealing mistake in season 3 - chronological order
Starring: Guy Williams, June Lockhart, Mark Goddard, Marta Kristen
Other mistake: In one of the opening scenes with Will and Dr Smith, the Robot's power pack is clearly missing.
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.