|Writers:||Peter Packer, Shimon Wincelberg|
|Principal Cast:||John Robinson (Guy Williams)|
|Supporting Cast:||Don Forbes as TV Announcer, Dawson Palmer as Bubble Creature|
|Preceded By:||The Reluctant Stowaway|
|Followed By:||Island in the Sky|
The Jupiter 2 encounters a derelict… an apparently abandonded spacecraft of huge dimensions and is drawn inside.
After leaving Earth and the Robinson party realizing that they are hopelessly lost in space, the ship is drawn into a giant derelict spaceship. The ship appears to be abandoned. John, Don and Smith make their way to the control room, then Smith wanders off to explore further. Meanwhile, Will (who left the ship contrary to orders) wanders off on his own exploration.
As John and the Major marvel at their discovery of intricate star maps, Will, then Smith, stumble onto a chamber where dozens of bubble creatures (obviously inhabitants of the ship) are in suspended animation. Their presence revives the creatures, with whom Will tries to communicate. Smith starts blasting them with a laser when Will expresses regret that they don't seem to understand him. While running for their lives, Smith and Will find the other men of the group, and they all race to the ship and barely make it before the creatures catch them.
The Jupiter 2 escapes.
- The final new footage from the Alpha Control two-story set is seen, along with a brief, low quality shot of the facility's exterior. After this episode the set was pulled down and its equipment used in other episodes.
- This is the last time Smith will try and contact 'Aeolus 14 Umbra', and indeed, that plot point is never mentioned again, except in clips from 'The Reluctant Stowaway'.
- The alien ship, together with the shots of the door opening and closing, and the landing sequence inside it, is reused in the third season in "Kidnapped In Space", when it becomes the Xenian ship.
- Except possibly the shot of Jupiter approaching Priplanus (and a revised appearance), and part of the opening scenes at Alpha Control, none of the original pilot's footage appears in this episode.
- Will's and Smith's actions come under scrutiny a year later when the Robinsons are indicted for assorted offenses and put on trial.
- This episode's musical score is unusual in that little of it was repeated in later episodes. Aside from the famous 'Family Theme', 'Frontal Robotomy' and the moody 'Derelict Title' which plays over the last shots of Alpha Control, the other parts of the score were dropped completely. (Occasional excerpts of 'The Treatment/Swallowed' and 'Rescued from Space' are the only others to appear). For Lost in Space this is an anomaly given that almost all the show's music was repeated continuously throughout the three seasons.
- This episode contains a blooper: when the Bubble Creatures are chasing the Robinsons to the Jupiter 2, the white shoes of the stage hands pushing the creatures occasionally come into shot.
- Priplanus, which first appears in this episode, has been redesigned from the planet seen in the original pilot shot. Possibly this is to avoid any mistaking the world with Mars as occurred in 'No Place to Hide', although a reference to this was left in a later pilot scene edited into 'The Hungry Sea'.
- A terrible piece of science is used in this episode: the comet near the Jupiter 2 is supposedly extremely hot- when in fact comets are made of ice!
- A strange error involves the Bubble Creatures from this episode. In the second series clip-show episode 'Prisoners of Space', the judge is one of the species yet has no trouble speaking english. Of course, those in this episode cannot communicate except by electrical sparks. This can be passed off as a writer's fault- or a deliberate gaff in order to shock Dr Smith- but it still makes little sense either way.