Continuity mistake: When Dr. Smith closes the door at the end when rehearsing the play, his cape is caught in the door. When the scene cuts back to the door a second later it is gone.
Lost in Space (1965)
1 continuity mistake in The Astral Traveler - chronological order
Starring: Guy Williams, June Lockhart, Mark Goddard, Marta Kristen
Visit to a Hostile Planet - S3-E2
Continuity mistake: When the guy shoots the Robinson Robot it leaves a big bullet hole on the front. In the next shot we see the Robinson Robot turning around and the bullet hole is gone.
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.