The paranormal makes a few appearances in Lost in Space. Somewhat surprisingly for a science-fiction series, the existence of paranormal phenomena is blandly accepted by characters on three occasions, and left open to question in another. Although most of the crew deny its existence, the issue itself is not answered definitively. In three episodes different forms of paranormal phenomena are a key element of some aspect of the plot. These paranormal concepts seen are telepathy in “The Keeper,” mediumship in “Ghost in Space,” and materialisation in “Space Circus,” as well as a ghost in "The Astral Traveller."
In “The Keeper: Part 1,” when the Keeper introduces himself to the Robinsons, John Robinson observes that one of the Keeper’s powers is mind-reading after seeing the visitor read Will’s thoughts. The Keeper admits that while he is capable of reading the boy’s thoughts, it is because they are pure; he implies that other apparent instances of mind reading are merely the astute reading of a person’s character. This ability of the Keeper, in tandem with the hypnotic signal emitted by his staff, make the apparent ease with which he is able repeatedly to summon Will and Penny to his ship during the episode quite plausible.
Dr. Smith produces a ouija board in “Ghost in Space,” an eerie and atmospheric episode that stands out as one of the best in the series in this respect. His intent is to use the talking board to contact the spirit of his Uncle Thaddeus on the anniversary of his death using Penny as a medium (presumably for her gentle and innocent qualities, as well as her being the only other member of the party not to scoff at his belief in the supernatural). What is most notable in this episode is that while it is clearly asserted that all of the supposedly supernatural phenomena that occur after Smith’s attempts to contact his late uncle are in fact explainable as natural events, Dr. Smith never once wavers in his firm conviction that they are in fact proof of the existence of the supernatural. This belief of Smith seems to be at odds with his normal characterisation of himself as a highly-trained scientist, but it is not inconceivable.
The third occurrence of paranormal activity takes place in “Space Circus.” In that episode, it develops by chance that Will seems to have a gift for making his thoughts materialise as physical objects. He does it successfully with a golden chalice and a purple frog, but has less luck when attempting to create an apple (he materialises a red wooden ball instead). It should be noted that Will does not have the ability to exercise this power on his own; it is only through the guidance of Fenestra, a performer in the circus, that he is able to visualise and materialise anything. After the failure to create the apple, we are happy to see Will successfully create (with Fenestra’s help, of course) a whacking great knife for his father to use in his battle with the cosmic monster.
"The Astral Traveller" features a ghost, Hamish, whom Will and Dr. Smith visit in the castle in which he is imprisoned in Scotland. The episode also features a monster, Hamish's Uncle Angus, who was transformed by a curse in punishment for his activities.
Other apparent occasions of the paranormal are ambivalent at best, and may better be attributed to the achievements of technology. For example, in “Invaders from the Fifth Dimension” the Robot reveals that he can read human thoughts because the human brain produces waves that he can intercept and reconstruct as words.