As the Jupiter 2 travels through space, Smith accidently launches the space pod with himself, Will and the Robot inside it. They are drawn into the gravitational pull of a nearby planet and forced to land. The Jupiter 2 tries to track them, but the pod seems to vanish off the radar scope. When they attempt to follow, they too are pulled into a crash landing on the planet. John contacts Will on the radio and tells the boy to stay put in the space pod while they come to get him. However, Will is perplexed that the description his father gives of the rocky area where the space pod is doesn't match the tropical area Will sees outside the pod window. Likewise, the Robinsons are confused when Will tells them he sees trees instead of rocks.
Despite John’s orders, Dr. Smith insists they all get out of the pod, and when they do so, they find themselves in a beautiful jungle. Heedless of the Robot's warnings to the contrary, Will and Smith decide to lie down and take a nap. When they wake up, they find the Robot covered in dirt and rust. After cleaning him off, they begin to walk to see if they can meet up with Don and John. They don’t find them, but they do end up finding the Jupiter 2 in a very aged condition and covered in vines. When they go in to have a look around, the place is in ruins and they don’t find a single member of their family.
Outside the dilapidated Jupiter 2 is a statue dedicated to the Robot. When Will reads the plaque at the base of the statue, they are shocked to read that it was erected in the year 2270. Somehow, they had been asleep for over 270 years.
Will is very depressed and concerned over the whereabouts of his family. His attentions are directed elsewhere when a raging army appears, followed by a giant cyclops. However, both of these things vanish before they cause any real harm. Two American astronauts arrive, claiming they are historians. They ask Will a few questions, and then they depart again.
Meanwhile, John and Don continue to search the planet for their missing crew mates. They arrive at the area where the scanner picked up the space pod’s signal, but they find nothing there. Confused, they have little option but to continue to look.
Will, Smith and the Robot explore a cave where they encounter an oddly dressed woman who looks exactly like Judy. Will greets her as such, but she claims she isn’t Judy at all. Rather, she is Judy’s great-great-great-grand-daughter. She takes Will aside to have a chat with him. A young astronaut appears and smacks Dr. Smith. He claims to be Smith’s great-great-great-grandson, but is not proud of it. He claims the name “Smith” is shameful to carry due to Dr. Smith’s disgraceful act of sabotage on the Jupiter 2. Dr. Smith, of course, feigns innocence and offers to do what is necessary to clear the family name. The young astronaut says Smith can board the mother-ship at dawn. Then he can testify before the Galactic Tribunal to clear himself of the charges. Dr. Smith agrees to do so, and the young astronaut leaves.
Judy’s descendant also tries to convince Will that the best course of action would be to get onto the mother-ship and leave the planet. Will refuses as he still holds out hope of finding his family. He leaves the cave, and Smith and Robot follow him. They go back to the jungle where they left the space pod but it is no longer there. They walk for a while, and eventually find the pod in an entirely different location. Will is very suspicious, having the feeling something very strange is going on around them.
John and Don also find what they believe to be the space pod, rusted and covered in vines. John refuses to be fooled, stating with conviction that it is only an illusion. With those words, the vines vanish and the space pod looks normal again.
Dr. Smith tries to convince Will to make the rendezvous with the mother-ship so they can leave the planet. Will firmly says there is no mother-ship. There was no statue, no rusted Jupiter 2, no astronauts. The whole ordeal has been an illusion, right from the moment they landed.
As Will speaks, a huge computer reveals itself nearby. The computer accuses Will of being an evil intruder, and demands that he leave. Will knows the computer is responsible for all the illusions. It is afraid and has been trying to scare them away from its planet. When Will refuses to go away, the computer creates another illusion: a monster and terrible flames. The Robot blasts the computer, and it explodes. The Robinsons are reunited and the strange illusions are gone for good.
Background information[]
- When will Dr. Smith ever learn not to push random buttons??
- Every time they have to land on a planet it's an "emergency landing" and they re-use the footage from the original pilot episode that showed the Jupiter 2 (Gemini 12) falling into the planet's atmosphere followed by a "crash" sound effect. The landing in this episode is no different. (Not EVERY time. "Visit to a Hostile Planet" and "The Ghost Planet" are just 2 examples off the top of my head where they didn't have a crash landing. But I'll grant you that it was a trope they used more than once just like that oft repeated shot that we first saw of Jimmy Hapgood's ship as it took off in Season 1's "Welcome Stranger".)
- From space the planet looks green so one would expect the sky on the planet to look green, but instead as the ship was landing and immediately after landing it looked blue. Later when John and Don are searching for the space pod, the sky looks a dark purple. Still not green.
- Once again the crew member fail to check atmospheric conditions on the planet(s) before disembarking.
- This episode has a short color clip of the cyclops giant, seen for the first time since The Keeper, Part II.
- Dr Smith is referred to by his 'descendant' as the "Fifth Columnist" of the Jupiter 2 expedition.
- Dr. Smith attempts to eat a peach, which springs out of his hand and explodes. He then states that "All this fruitless activity has done me in; I think I'll take a little nap.".
- The space suits worn by the "Space Historians" were created originally for the classic SF film Destination Moon.
- What is the point of the space historians wearing space suits if will and dr. smith can breathe fine. not only that,the spacesuits have large holes in their visors, which makes them pointless, even if the atmosphere was toxic
- The scene showing the triceratops-looking monster is reused from "The Space Primevals" three episodes previously.
- The Emerald Planet external visual is a re-use of the Sun visual from "Wild Adventure", with green tint added.
- It's interesting to note how much the computer creating the illusions knew about the crew of the Jupiter 2 in order to create such elaborate and believable illusions about them. It's especially surprising the computer knew about Smith's lack of character and his sabotage of the Jupiter 2.
- It's surprising the Robot was so quick to destroy the computer creating the illusions on the planet. After all, the computer was one of the Robot's own kind, and seemed like a sympathetic figure who was simply afraid. One would think the Robot would be interested in trying to preserve the computer and instead try to reason with it to convince it that the Robinsons weren't a threat. Even if the last monster created by the computer was real, it seems the Robot could've destroyed the monster instead of the computer and then tried to reason with the computer some more. (THEN AGAIN, appeasement didn't work with Hitler and doesn't work with anyone or anything devoted to manipulation, deception, and domination as that computer clearly was.)
- Didn’t Smith already accidentally launch the Space Pod a few episodes ago in “Kidnapped in Space”? Why don’t they make a policy of forbidding him to go in there?
- Doctor Smith becomes indignant and insulted over the idea of having to give the Robot a rub-down. However, in the episode “War of the Robots” Smith willingly rubbed the Robot daily for two weeks.