- The three races on Malacandra - hrossa, séroni, and pfifltriggi - is later adopted into other novels after Lewis' death. Larry Niven's Rainbow Mars, Ian Edginton D'Israeli's Scarlet Traces, and also a comic series League of Extraordinary Gentlemen all exist as Martian species in their own setting.
- C.S. Lewis received a handful of complaints on his "science" in Out of the Silent Planet. People have argued that the physics applied to the novel did not agree with their reality. Eventually, Lewis replied that everything he said in his story was "mumbo jumbo".
- In the final chapter of the story, C.S. Lewis introduces himself as one of the characters in the novel. He is presented as a close friend of Dr. Ransom and how they have agreed to publish Out of the Silent Planet to let others know of the Martian's existence.
- The language the three races speak is originally from the hrossa's tongue. The séroni, and pfifltriggi do have their own languages, but they do not do so very often in public with other races.
- One of the reasons C.S. Lewis wrote this book was due to an agreement between J.R.R Tolkien and himself. Lewis said he would write a sci-fi novel while Tolkien wrote a time-travel one, known as The Lost Road and Other Writings (1987).
Sources: https://en.wikipedia.org/wiki/Out_of_the_Silent_Planet
