The Jupiter 2 is pulled into a giant alien spaceship where there are advanced bubble-like creatures. While John and Don look for maps and equipment Dr Smith and Will look for trouble.

Professor Robinson attempts to explore a planet that the Robinson's are planning to land on. His para-jet propulsion system fails due to sabotage by Dr. Smith. Major West "lands" the Jupiter II, in spite of the fact that Dr. Smith has also sabotaged the propulsion system of the Jupiter II, and the family and Major West rescue Professor Robinson.

Jimmy Hapgood lands on the planet and the Robinsons befriend him.After helping him fix his spaceship the Robinsons try and convince him to take Will and Penny back to Earth with him.But Dr Smith trys to get aboard the ship back to Earth.

Smith eats some alien fruit which transforms him into a giant. Convinced it was the Robinsons trying to kill him, he plots to take them out.

Lost in Space's only Christmas program. Will uses an alien transporter to send himself back to earth. However, many people believe the Robinson family to be dead after hearing the ship went off course. Nobody on Earth believes him, and they lock him up with the intention of sending him to a boys' home.

Will escapes the family home he's in, and wanders around these clueless bunch of townspeople, but finds carbon tetrachoride — needed for the food processors on the Jupiter. Eventually he convinces another boy, Davey, to let him out, and let him return to the planet he came from. He returns to Priplanus with this bottle. Of course no one believes his adventures until he produces the bottle, plainly labeled as coming from Earth.

The Robinsons meet a space traveler who turns out to be an Earth man, Alonzo P. Tucker, who was abducted from Punxsutawney, Pennsylvania, by aliens, in 1876. Tucker befriends Will by telling tall tales about being a pirate, but it turns out that he is only an ordinary man being pursued by aliens because he has stolen a mind reading device from them. Tucker returns the mind reading device to his alien pursuers, saving the Robinsons in the process.

Penny and Judy stumble upon a mirror. They discover someone is on the otherside. Before they know it they are transported to the mirror universe which is occupied by only one person, a boy who is lonesome for companionship.

Dr. Smith is conscripted as the leader of a people from another world. Little does he know that the leaders of these people are routinely sacrificed and replaced with other expendible leaders. Smith is just one of a long line of sacrificed rulers.

The Robinson men discover an underground civilization while exploring the planet. Will wakes a sleeping princess who wants him to remain and rule with her.

Shortly after leaving their original crash-site planet, Smith spots a familiar star and, in an amazing show of stellar navigational skill, calculates the course to get back to Earth.

He extracts a promise from Don and John that they'll return to Earth, or else he'll destroy his navigation data. They agree, but inform the family at dinnertime that they are headed for Alpha Centauri after all, mainly because the Earth is on the other side of the Sun (how do they know that? - do they know the date? And besides, from Alpha Centauri, Earth revolves clockwise, visible all the time). Smith changes course 180 degrees, then clumsily jettisons most of the fuel.

They reach a refueling barge, one of several that Alpha Control put out in 1996, top up the tanks, and resume course for Alpha Centauri, not knowing that they've picked up a tailgater who follows them after Smith reverses course to Earth again.

The alarm goes off in the night, and they expend a lot of fuel pulling away from the Earth's

The Space Family Robinson go through a food crisis when their plant purifier breaks down. Will and Dr Smith discover a travelling show of circus people, and Will is later tricked in to agreeing to join. It's a race against time for the Robinsons to save will, and keep themselves alive.

When a troope of Galactic Gladiators arrive on the planet, they challenge Professor Robinson to a duel, which will be aired all of the galaxy. John declines saying he isn't interested in physical combat. Dr Smith takes up the offer when he makes a deal that if he wins, he will be returned to Earth. Unbeknownst to him, if he loses, which is a near-certanty, Earth will be destroyed.

While playing a outdoor match, Will and Smith's ball explodes, and as the smoke clears there ball has turns into gold. the ball rolls into the cave which has 3 aliens inside, the alien wants the robot , which is later stolen when Will refuses to let them have it and Smith does. Can the crew get there robot back.

During a heat wave, Penny comes across a giant, golden man, and his owner. She is told that the creature is called Raddion, a creation which only needs human emotions to be complete. When Dr Smith is removed from the camp, he is taken by two midgets who work with Raddion, and in another atempt to be returned to Earth, agrees to get the emotions from the Robinsons. He does so by taking their pictures, and all that is needed is for the Robinsons to shake hands with him. Don protests and heads back for camp, as do the Robinsons minus their emotions. Eventually they are returned to normal and it is learnt that human emotions cannot be bought or stolen.

Will and Dr Smith are confronted by a knight, who says he is on a quest to seek out and destroy the beast Gundemar. Penny, meanwhile, meets Gundemar and befriends her. Will becomes the pageboy of the knight. When it is discovered that the beast is woman, the knight is unsure whether he can still kill it, leading him to question his life's future.

A storm looms up and the two gloves of Thor appear from space and straight into the waiting hands of Dr. Smith. Then are then taken away to see the real Thor who will decide there fate.

Dr. smith hits his head on a rock and goes into the depths of a cave where he finds a mummy, meanwhile the crew have to blast off at 8:00am, and while the also have to rescue Dr. Smith.

The Robinson's communications system is knowcked out, and they discover that the culprit is a female warrior, who is planing on making this planet a colony for her people. She encaptures the members of the Robinson camp, and puts the men to work clearing a landing platform and erecting an arc. Meanwhile she keeps the females seperate and teaches them of the virtues of females, and the vices of males. Dr Smith becomes her escort to get out of work. Just before her colonists arrive, John, Will, Don and Dr Smith destroy the arc, and the colonists leave. It ends with Noble Neolani questioningthe value of men, and perhaps they weren't as bad or stupid as she thought.

Dr Smith and Will become trapped in a cave during a cosmic storm. Will is accidently pulled through a cosmic time warp, and ends up on Earth, in Scottish castle. He meets a headless ghost called Hamish who was beheaded at the Castle. Hamish is trapped there due to the callous crimes he has committed. They rest of the family manage to get Will out, but Hamish follows him. They decide to re-create the time warp, and send Hamish home, and with him Dr Smith, carrying star-charts and maps so that he may send a rescue mission to save the Robinsons. Upon re-entering the warp, Dr Smith drops the charts, and Will runs after him to give them to him. They are both taken. When they reach the castle again, Dr Smith and Will realise that they are not in their time. Also, Hamish becomes angry when he realises that Dr Smith is a liar, and has no intention of helping the Robinsons. As an act of reveng he sets out to destroy Dr Smith. In the end, Will and Dr Smith return to the planet, and Ha

The Jupiter 2 and all aboard are caught in a space 'time-warp'! After everything seems to return to normal, they're shocked to find Earth within their reach and decide to return home. Though they're perplexed that they are unable to contact 'Alpha-Control', they decide to land in the 'good ole USA' ....only to find it's 1947! As usual, Dr. Smith causes issues & even considers staying behind when the Robinsons and West announce plans to leave.

In an episode reminiscent of the first season episode "The Challenge", Professor Robinson and the Robot land the Space Pod on a planet, and Professor Robinson kills an attacking monster, only to discover that he has interfered with a contest where a highly intelligent alien who aspires to rule his home planet is being judged on how well he hunts. The alien forces Professor Robinson to take the role of one of the hunted animals in the contest, allowing the Professor one weapon. The weapon has a defect that imperils Professor Robinson, but the Professor outwits the alien and survives the ordeal.

Dr. Smith and the Robot are exploring a cave. Smith pushes several buttons on a conspicuous control panel. The buttons activate a cyborg creating device. It up to Will to stop Dr. Smith.

A strange blue fog seems to be engulfing the Jupiter 2 periodically. Dr Smith and Will commment seperately that they want to be left alone. When the members of the Jupiter 2 begin to randomly disappear as the fog comes, Dr Smith thinks he is to blame. Eventually Will discovers a strange creature which takes over Dr Smith. The creature tells Will that he is his own Id. Will finds out his Id is a creature he created full of Will's own personal demons, thoughts, feelings and insecurities. Will defeats the creature by overcoming his ""fears"" and throws the powerless creature in the power core. The members of his family are returned.

A caveboy appears and attempts to lure Penny away, but she refuses, and is instead caught in a net. She is transported to an intergalactic zoo, were she will be puton show, meanwhile Dr. Smith tries to take over the zoo.

The Robot suddenly announces that the Jupiter II is approaching Alpha Centauri. Everyone is suprised, and the ship lands on a planet, where they are greeted by a group of people who appear to be teenagers from Earth. It turns out that they are aliens who live like Earth-style hippies, and they are incapable of growing old. They want to age normally, and to do this they want to get the older members of the Robinson party to leave in the Jupiter II while the younger members can stay behind and be used in an experiment that will make it possible for them to do so. The aliens trick the older members of the Robinson party into leaving, but Will pulls a fast one on the aliens and the Jupiter II eventually returns to the planet, and Penny, Will, and Dr. Smith, who somehow passed himself off as a young person, are rescued.

The galactic showman, Farnum B returns as the producer of the Miss Galaxy Beauty Pageant. They want to Judy to be in the contest, she doesn't want to but Dr. Smith for forges her name and the fun begins.

Dr. Smith disposes of a plant that has grown out of control, but once outside the plant attaches itself to the Jupiter 2. The plant apparently believe that Dr. Smith is its mother, meanwhile the ship is attached by a brave space warrior.