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Beam Me Up, Scotty!: Despite the popularity of the phrase, Robot B-9's infamous catchphrase "Danger, Will Robinson!" is said exactly once in the original show, in the episode "The Deadliest of the Species". The phrases "Warning" and "Danger" would be would used throughout the series, however.
Dueling Shows: The great contemporary rival of Star Trek, which CBS passed over for this series. (Ironically enough, after several mergers and acquisitions, CBS now ownsStar Trek...but the head of CBS won't have a Star Trek show on CBS, the CW, or Showtime.)
Fake American: Both daughters are played by non-American actress (Marta Kristen, who played Judy, is originally from Sweden; while Penny's actress, Veronica Cartwright, is British).
Missing Episode: The unaired and originally unsyndicated Dr Smith-less original pilot.
Throw It In: When the episode guest-starring Al Lewis came in a couple minutes short, Lewis suggested they fill it with a routine he'd used in his vaudeville days, with Dr. Smith repeatedly turning around on his way into the spaceship to mention something he'd forgotten, to Lewis' increasing frustration.