This is the sixteenth and final episode to feature Dawson Palmer, portrayer of many Lost In Space monsters, creatures and androids.
This is the only time in which the nuclear reactor at the very bottom of the J2 is shown. It is rather curious, that in the area where the small stairs leading to the reactor is located there are many boxes, including some marked food concentrate, as in some episodes there was little food available for the space travelers.
Dr. Smith quotes from Matthew 16:23 - "Get thee behind me, Satan!"
Smith says, "From the depth of Gehenna to the steps of the throne, he travels fastest who travels alone. Shakespeare." Will says, "It's Kipling." Almost; the line is "Down to Gehenna or up to the Throne, he travels the fastest who travels alone." Kipling's poem "The Winners" describes the philosophy of the Gadsbys, a philosophy of utter greed, of self-interest, of vanity, and of using others: "His be the labor and yours be the spoil. Win by his aid and the aid disown- He travels the fastest who travels alone."
This episode is very reminiscent of Star Trek the Next Generation, episode "Skin of Evil". Armus wanted to learn about fear.