There Were Giants in the Earth - S1-E5
Revealing mistake: The Robot's lights wink out for a few seconds as it disables the force field.
Lost in Space (1965)
1 mistake in There Were Giants in the Earth - chronological order
Starring: Guy Williams, June Lockhart, Mark Goddard, Marta Kristen
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.