Throughout the book, the Robinson's ship is referred to simply as the Jupiter instead of Jupiter 2.

On page 2, Dr. Smith, in his nightmare, reflects on armored spiders found on the Proteus. This refers back to events in Lost in Space.

Will's most recent reprogramming of the Robot's AI software has resulted in the mechanical marvel's current tendency to spout clichéd platitudes. On page 4, the Robot says, "Run away and live to fight another day!" The currently popular idiom is "He who fights and runs away will live to fight another day." The idiom is derived from a quote by Demosthenes in 338 BC, who, after fleeing from a battlefield, defended himself with, "The man who runs away may fight again."  

On page 5, with the ship confronted by a space-pirate ship, Don suggests to John that maybe it's time they "headed through the sun again." This is a reference to the hyperjump the Jupiter 2 made through Earth's sun in Lost in Space.

On page 19, the Robot says, "I make it a practice to believe in at least one impossible thing before my morning diagnostic routine." This is a play on a statement made by the White Queen to Alice in Lewis Carroll's 1871 novel Through the Looking-Glass, "Why, sometimes I've believed as many as six impossible things before breakfast."

Also on page 19, Will's dark side rains on his Pollyanna half's parade. Pollyanna is a character appearing in a number of children's novels; she is known for an unfailingly optimistic attitude.

On page 24 (and elsewhere in the novel), notice that Will refers to the Robot as "he", while his father stresses "it". It's a nice juxtaposition of Will considering the Robot a friend, while John considers the Robot a tool.

On page 34, Dr. Smith thinks of his nemesis, Don, as a mesomorph. A mesomorph is an entity that exists between the states of solid and liquid, i.e. gelatinous. He is probably referring to Don in his estimation of the pilot/soldier's mental capacity.

On page 48, John recalls his youth, when he and some pals had viewed some gross-out Surroundvids. Presumably, Surroundvids are a type of movie or VR entertainment.

On page 55, Judy is relieved to find that the inhabitants of Rellka are at least aware of the existence of other worlds. This may be a reference to the society the crew found aboard the sphere they encountered in Promised Land, the citizens of which largely did not acknowledge the existence of anything outside their interior world.

During his session in the cubicle on page 57, Dr. Smith sees members of his own family: his parents and some uncles and aunts. The omission of any mention of siblings hints that he was an only child.

On page 63, Judy compares the cubicles to being possibly like the Roman Coliseum as a source of despicable entertainment. She is referring to the slaughter of often innocent people by gladiators, animals, or each other in the Amphitheatrum Flavium (now known as the Roman Coliseum) in the ancient Roman Empire of Earth.

On page 68, Judy reflects on the fact that, while Smith may be a doctor, he does not place any value on the Hippocratic oath. This is the oath taken by western doctors to obey a certain code of ethics. The original version is believed to have been written by Hippocrates in ancient Greece.

Page 72 reveals that John and Don have placed a number of lockouts on controls of the Jupiter 2 to prevent Dr. Smith from gaining access to the ship's important systems.

On page 73, Judy muses on some seeming lapses on Dr. Smith's part over the last few months when he'd seemingly put someone else's welfare on a par with his own.

Page 74 mentions the time Judy spent helping Dr. Smith get through detox. This must be a reference to Smith being forced by Judy to get off the drug called the Kiss he'd been manufacturing on the ship and using in Promised Land.

Page 82 reveals that Will has devised three multijointed, gyrostabilized legs for the Robot, so it could more easily travel over all types of terrain. It has previously maneuvered on two treads.

On pages 106-107, Will tries to remember what passphrase he last programmed into the Robot to allow him to override its current orders. He remembers that he'd been viewing old 20th Century pop culture entertainment in the ship's library when he developed the new phrase and so he tries various ones until the Robot responds. Will first tries "Shazam!" "SHAZAM" comes from the Captain Marvel comic books published by Fawcett Comics from 1939-1953 and later by DC Comics and was the magic word spoken by young Billy Batson to transform into the powerful Captain. (SHAZAM is an acronym for the mythological gods whose powers he receives when he transforms into Captain Marvel: the wisdom of Solomon; the strength of Hercules; the stamina of Atlas; the power of Zeus; the courage of Achilles; and the speed of Mercury). Will then remembers the correct phrase, "Holy Takeover Scenario, Robotman!" This is a play on the phrasings Robin would use to Batman on the 1966-1968 TV series Batman. Responding to the passphrase, the Robot thunders, "To the Robot Cave, Boy Wonder!" This is a play on Batman's frequent use of "To the Bat Cave!" or "To the Bat Cave, Robin!" and "Boy Wonder" was one of Robin's nicknames.

On page 144, Will reflects on how he occasionally finds that his hacker solutions to computer/electronic problems have what should be an obvious flaw, the equivalent of division by zero in math problems. In mathematics, division by zero is undefined since multiplication of any number by zero always equals zero.

On page 157, Will reflects that his father, despite his brilliance, was not infallible and compares him to Einstein, who'd formulated the theory of relativity and who frequently forgot "to put his socks on." Einstein, of course, is a reference to Albert Einstein, the renowned German theoretical physicist who refused, during a visit to America in the 1930s, to return to Germany after Hitler came into power, and became an American citizen. He did formulate the general theory of relativity. According to lore, however, he did not so much forget to wear socks as he consciously chose not to wear them, finding them redundant if one's feet were already going to be encased in shoes and, besides, ones toes always wound up wearing uncomfortable holes in the socks anyway!

In an attempt to find a way to counter Dr. Smith's newfound psychic abilities, Maureen studies up on such phenomenon in humans from the ship's library, with her only reliable findings being Rhineian studies of the past century-and-a-half. This is a reference to the real world Dr. Joseph Rhine (1895-1980), a botanist who developed an interest in parapsychology and began scientific studies of it at Duke University and founded the Journal of Parapsychology and the Foundation for Research on the Nature of Man (now known as the Rhine Research Center).

Several times in the book, Penny thinks of herself as the Space Captive. She was first depicted referring to herself thusly in Lost in Space, having been brought along with her family on their mission to find a new Earth against her own wishes.

Pages 163-166 reveal that Penny kind of likes Dr. Smith, despite his treacherous ways, and wouldn't mind so much if he took command of the ship, believing he'd be more proactive in getting the ship back to Earth without the sightseeing and hand-wringing her father tends to engage in.

On page 191, Dr. Smith recalls watching a "prehistoric" entertainment vid called something like the Elvis Sullivan Show. He is obviously thinking of the 1948-1971 Ed Sullivan Show and probably confusing the name with several controversial appearances by Elvis Presley on it.

Page 205 mentions that Maureen is a xenobiologist, but she wishes, in the current circumstances, that she were a xenopsychologist and xenohistorian. The prefix "xeno" means "alien".

On page 210, Will hopes the Robot won't break into a rendition of the song "Whistle While You Work". This is a song written by Larry Morey and Frank Churchill for the 1937 animated Disney movie Snow White and the Seven Dwarfs.

On page 211, the Robot insists on entering the Vault before Will, stating, "You know the rules about harm and inaction." The Robot is referring to the first of Isaac Asimov's original Three Laws of Robotics in his Robot stories. The First Law states, "A robot may not injure a human being or, through inaction, allow a human being to come to harm."

Page 217 reveals that Dr. Smith had hidden a number of virus-like programs in the ship's computer over the months of their journey through space, in hopes of triggering them to his benefit at some point in the future. Will has found them all during the events of the novel, however, and eliminated them.

Upon seeing Don on page 231, the Robot says, "Mazel tov, kemosabe!" "Mazel tov" is a Yiddish phrase for expressing congratulations. "Kemosabe" is the word used by the Lone Ranger's American Indian friend, Tonto, as a term of friendship and respect for the Ranger.

On page 232, the Robot uses the phrase "come a cropper". This is a British phrase which essentially means "to fail badly".

Page 238 reveals that there is a set of rarely-used stairs leading to the bridge from the lower deck of the Jupiter 2.

On page 251, Judy remarks that her sister Penny is fond of saying "do the math". Penny used this phrase in Lost in Space.

On page 259, the Robot says, "What the Vault gives, the Vault can take away. Praise be the Vault." This is a paraphrasing of phrases sometimes used by those of Christian faith in describing the actions of God.

Page 270 uses the phrase "Hitlerian dictatorship". This is obviously a reference to Adolf Hitler, Chancellor of Germany 1934-1945, who established a fascist government there. 

On page 289, the Robot refers to Will as "sahib". "Sahib" is an Arabic word, essentially meaning "friend" in modern parlance, which has passed into numerous other languages.

On page 293, Will threatens to stop his father's heart with his new psychic abilities if the Robot doesn't put him down. The Robot responds, "How sharper than a serpent's tooth--" before Will cuts him off. The Robot is quoting a line in Shakespeare's 1605 play King Lear. The full line is "How sharper than a serpent's tooth it is, to have a thankless child!"

Page 304 reveals that Dr. Smith, though now deprogrammed of his psychic abilities, did retain the unfortunate (from his point of view) beginnings of empathy for the Robinsons, from his recent telepathic contacts with their minds.

At the end of the novel, the Robot still has his three legs instead of the former treads, so future stories in the series would presumably depict him thus, if they mentioned his legs at all.

By the end of the novel, it could be argued that the story presented is based on that of the 1956 film Forbidden Planet, which itself is a science-fictional take on Shakespeare's play The Tempest. In Forbidden Planet, the crew of an Earth ship learn of the self-extinction of a technologically advanced species called the Krell through the beings' own submerged inner evils brought to the fore psychically. Here, the Rellkans (notice the similarity to the name of the Krell) were nearly destroyed in a similar manner.

Unanswered Questions

Where is Blarp? The creature is not mentioned or seen in the entire novel. Presumably, she is still in a hibernation tube, as previously described in Promised Land.