Revealing mistake: When building the shelter, it takes both John and Don to lift the supposedly heavy panels; however when upright the panels bend easily when gripped. Obviously some sort of styrofoam/aluminium foil prop.
Lost in Space (1965)
1 revealing mistake in The Hungry Sea - 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.
Robot: My micromechanism thanks you, my computer tapes thank you, and I thank you.
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.