In the observatory, the astronomer is studying at his desk. Satan appears, then a woman appears and makes Satan vanish. Then she disappears. The astronomer draws a globe on a blackboard. The globe develops a sun-like head and limbs and starts to move on the blackboard. The astronomer looks through a small telescope.
Set in the future, the film's prologue depicts Jim Hawkins as a five-year-old (voiced by Austin Majors) reading a storybook in bed. Jim is enchanted by stories of the legendary pirate Captain Flint and his ability to appear from nowhere, raid passing ships, and disappear in order to hide the loot on the mysterious "Treasure Planet". Twelve years later, Jim (Joseph Gordon-Levitt) has grown into an aloof and alienated teenager. He is shown begrudgingly helping his mother Sarah (Laurie Metcalf) run an inn and deriving amusement from "solar surfing" (a hybrid of skysurfing and windsurfing atop a board attached to a solar sail-powered rocket), a pastime that frequently gets him in trouble.
In the future world of 1980 the United States Air Force's Space Exploration Wing has bases on the moon and is on the eve of a mission to Mars. When yet another of their Pegasus spacecraft with its two-member crew mysteriously disappears leading to rumors among the ranks of "space monsters" and "phantom planets", Mars mission pilot Captain Frank Chapman and his navigator Lt. Ray Makonnen are sent to investigate in their own Pegasus craft.
Financial disaster looms for Grand Fenwick when the current vintage of its only export, wine, starts exploding in would-be consumers' faces. Prime Minister Mountjoy (Ron Moody) decides to ask the United States for a loan, ostensibly to fund its entry in the race to the Moon, but actually to save the duchy (and install modern plumbing so he can have a hot bath). The devious politician knows that the Americans will not believe him, but will consider the half million dollars he is asking for to be cheap propaganda supporting their hollow call for international co-operation in space. He is delighted when they send him double the amount as an outright gift. The Soviets, not wishing to be one-upped by their Cold War rivals, deliver an obsolete rocket. Mountjoy asks resident scientist Professor Kokintz (David Kosoff) to arrange a small explosion during the "launch" of their lunar rocket to make it look like they have actually spent the money as intended.
In the British city of "Everytown", businessman John Cabal (Raymond Massey) cannot enjoy Christmas Day, 1940, with the news everywhere of possible war. His guest, Harding (Maurice Braddell), shares his worries, while his other friend, the over-optimistic Pippa Passworthy (Edward Chapman), believes it will not come to pass, but if it does, it will accelerate technological progress. An aerial bombing raid on the city that night results in general mobilisation and then global war.
The film begins with footsteps leading to a pond. The camera continually moves upwards to show the flight of butterflies, birds, and a progression of historical aircraft ending with a rocketship travelling through space and landing on the moon.
Commando Cody (George Wallace) is a civilian researcher and inventor with a number of employees. He uses a streamlined helmet and a sonic-powered rocket backpack attached to a leather flying jacket. Cody also uses a rocket ship capable of reaching the Moon. When the U. S. finds itself under attack from a mysterious force that can wipe out entire military bases and industrial complexes, Cody surmises (correctly) that the Earth is coming under attack from our own Moon. He then flies his rocket ship there and confronts the Moon's dictator, Retik (Roy Barcroft), who boldly announces his plans to both conquer Earth and then move the Moon's entire population here using spaceships.
A bamboo cutter named Sanuki no Miyatsuko discovers a miniature girl inside a glowing bamboo shoot. Believing her to be a divine presence, Miyatsuko and his wife decide to raise her as their own, calling her "Princess". The girl grows rapidly and conspicuously, marveling her parents and earning her the nickname "Takenoko" (Little Bamboo) from the other children in the village. Sutemaru, the oldest among Kaguya's friends, develops a particularly close relationship with her.
In 1967, two young friends, Stas and Andrei, arrive to the newly built Star City (near Moscow) where the first cosmonauts trained to go into space, and where a race against the clock to beat the Americans into space takes place.
An atomic rocket is launched on a manned moon mission, but one of the engines malfunctions. The rocket's steering is broken. The pilot disengages the capsule and returns to Earth. The atomic booster, however, continues on, eventually crashing into and exploding in an asteroid belt. The explosion dislodges many asteroids from their orbits. They coalesce into one giant cluster and are heading for earth. As the cluster approaches earth it causes global scale disasters: tidal waves, wind, fire storms and earthquakes. One scientist loses his sanity in the crisis and disables the great computer needed to calculate all the firing data. He is stopped and the data provided. When there seems to be no reasonable hope that humans could eventually avoid the crash, scientists find that the moon will pass in front of the cluster so that the Earth will be shielded from most of it. However, a small part of the cluster is not shielded and goes towards the Earth. At this point, mankind's only hope is to arm every missile on earth with a nuclear warhead and fire them all at the cluster. The nations of the world band together and fire the volley. The cluster is destroyed.
Phineas T. Barnum (Burl Ives) and friends finance the first flight to the moon but find the task a little above them. They attempt to blast their rocket into orbit from a massive gun barrel built into the side of a Welsh mountain, but money troubles, spies and saboteurs ensure that the plan is doomed before it starts...
The film follows the adventures of Baron Munchausen, who is prompted to travel to the moon by his cousin Sirius, an astrologer convinced that it is inhabited by an ancient race called the Selenites. The Selentites incidentally possess the secret of immortality. The Baron takes up his cousin's offer and travels to the moon using a tall masted ship pulled by three hot air balloons and he is aided by his super-ability friends (who are from the prequel to this film, The Fabulous Adventures of the Legendary Baron Munchausen). When they reach the moon, they are initially placed in jeopardy as their craft lands in a crater and they fall into a subterranean sea inhabited by monsters; however, the Selentites come to rescue them and take them back to their kingdom where they meet the King and Queen. However, while he is there with his friends, the moon is invaded by the Green Meanies, led by the ostentatious Trivert, who will stop at nothing to get the talisman of eternal life for themselves. They manage to defeat the meanies and they are awarded the talisman for themselves and for Sirius - and they gain the secret of eternal life. The film ends with the Baron and Sirius at the end of the 20th Century, in a futuristic world inhabited by flying cars and skyscrapers reminiscing on their adventures.
In the year 1946, the Soviet space program is undergoing turmoil. Professor Sedikh, who is planning to lead the first manned exploration to the moon, is denounced by his rival Professor Karin as being too old and too mentally unstable for the mission. Professor Sedikh, aided by his assistant Marina and a youth named Andryusha, disregard Prof. Karin’s authority and make a successful landing on the moon. Although a few problems occur at the moon, including the discovery of a damaged oxygen tank and Professor Sedikh’s becoming trapped under a fallen boulder, the expedition is a success and the cosmonauts return to Moscow.
At a meeting of the Astronomic Club, its president, Professor Barbenfouillis, proposes a trip to the Moon. After addressing some dissent, five other brave astronomers—Nostradamus, Alcofrisbas, Omega, Micromegas, and Parafaragaramus—agree to the plan. They build a space capsule in the shape of a bullet, and a huge cannon to shoot it into space. The astronomers embark and their capsule is fired from the cannon with the help of "marines", most of whom are played by a bevy of young women in sailors' outfits. The Man in the Moon watches the capsule as it approaches, and it hits him in the eye.
The film begins in an unnamed war-torn European city in the late 18th century (dubbed "The Age of Reason" in an opening caption), where, amid explosions and gunfire from a large Turkish army outside the city gates, a fanciful touring stage production of Baron Munchausen's life and adventures is taking place. Backstage, city official "The Right Ordinary Horatio Jackson" reinforces the city's commitment to reason (here meaning uniformity) by ordering the execution of a soldier (Sting in a cameo) who had just accomplished a near-superhuman feat of bravery, claiming that his bravery is demoralizing to other soldiers.