Continuity mistake: When John is trapped in the electrical anomaly he tries to answer the radio and it is shown exploding. When Don and Judy start rescuing John you can notice the radio is still there, one shot with the antenna up and one without, and another with no radio.
Lost in Space (1965)
1 continuity mistake in Island in the Sky - 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.
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.