Visible crew/equipment: When Will and Dr. Smith first come upon the Trader's encampment, just as the dogs start to attack you can see the head of a crew member (dog trainer?) bob in and out of view from directly behind where the dog on the right was lying...from behind the boxes stacked on the ship's platform. (00:08:38)
Lost in Space (1965)
1 visible crew/equipment mistake in season 1
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.
Robot: Danger, Will Robinson! Danger.
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.