The evil Dr. Krupp (Luis Aceves Castañeda), also known as "The Bat", plots to steal a valuable Aztec treasure from the tomb of a centuries-old living mummy, Popoca (Angel di Stefani). Krupp builds a robot to defeat the mummy. Krupp's former colleague Dr. Eduardo Almada (Ramón Gay) and associates work to stop the mad scientist from creating his robot.
The films starts with Astrophysicist Ryoichi Shiraishi, his fiancee Hiroko, his sister Etsuko, and his friend Joji Atsumi witnessing a festival at a local village near Mount Fuji. Shiraishi then tells Atsumi that he has broken off his engagement with Hiroko but gives no reason other than an undisclosed obligation to remain in the village. A mysterious forest fire is then seen near them. Shiraishi rushes out to investigate and disappears during the confusion.
A huge, blinking flying saucer that's approaching the Earth emits a glowing object. This object races ahead of it to intercept a man who's driving down a lonely road. It takes over the man's body and directs him to Central Labs, a U.S. research facility that's been tracking the saucer (supposing it to be an asteroid).
The Invisible Boy is a mixture of lighthearted playfulness and menacing evil. As it begins, ten-year-old Timmie Merinoe (Eyer) seems only to want a playmate. After he is mysteriously invested with superior intelligence, he reassembles a robot that his father and other scientists had been ready to discard as unrepairable junk. No one pays much attention to the robot, named Robby, after Timmie gets it operating again, until Timmie's mother becomes angry when her son is taken aloft by a huge powered kite that Robby has built at Timmie's urging.
In the 23rd century, to discover the fate of an expedition sent 20 years earlier, starship C-57D reaches the distant planet Altair IV. Dr. Edward Morbius (Walter Pidgeon), one of the expedition's scientists, contacts the starship. He states no assistance is required, warning the Earth ship away, saying he cannot guarantee their safety. Commander John Adams (Leslie Nielsen) insists on landing.
After a botched attempt at suicide, Nora King (Kathleen Crowley) revives and discovers that her building has no electricity or water. She soon realizes that Chicago is deserted when she wanders out into the empty, quiet streets. Stumbling over the body of a dead woman, she encounters Frank Brooks (Richard Denning), another person who has just recently revived after being beaten in a robbery.
Nyah, a female alien commander from Mars, dressed in shiny black vinyl, heads for London in her flying saucer. She is part of the advanced alien team that is looking for Earth men to replace the dying male population on her world. Because of damage to her saucer, caused by entering Earth's atmosphere and then colliding with an aircraft, she is forced to land her damaged flying saucer in the remote Scottish moors, near a local village. She is armed with a raygun that can paralyze or kill, and she also has a tall, menacing robot named Chani.
At his underground laboratory in Los Angeles, Professor Nordstrom (Taylor Holmes), worried that manned space exploration is too dangerous, enlists the help of Dr. Ralph Harrison (Charles Drake), who recently left the new government-appointed Civil Interplanetary Flight Commission. The two scientists embark on a research project to create a robot that can replace a human for space flight. Nordstrom's daughter, Janice Roberts (Karin Booth), and her 11-year-old son Brian (Billy Chapin), nicknamed “Gadge”, become very interested in the project.
Evil Moon robot Ro-Man Extension XJ-2 (George Barrows), referred to as just Ro-Man, has seemingly destroyed all human life on Earth with a Calcinator death ray, all except for eight humans that remain alive. The survivors are an older scientist (John Mylong), his wife, two daughters, his young son Johnny (Gregory Moffett), his assistant, and two space pilots that shortly take off in a spaceship for an orbiting space platform. All eight have now developed an immunity to Ro Man's death ray, having received an experimental antibiotic serum developed by the scientist.
When a flying saucer lands in Washington, D.C., the U. S. Army quickly encircles the spaceship. A humanoid (Michael Rennie) emerges, announcing that he has come in peace. As he advances, he unexpectedly opens a small cylindrical device and is shot by a nervous soldier who thinks it's a weapon. A tall robot emerges from the saucer and quickly disintegrates the army's deployed weapons with an energy ray. The alien orders the robot, Gort, to stop. He explains that the broken device was a gift for the President, which would have enabled him "to study life on the other planets".
There is a mouse invading Porky Pig's house, but so far Porky's attempts to rid the mouse have failed. Porky gets a cat to catch the mouse, only for the cat to get bound and launched out of the house. Next Porky borrows a mountain lion, but the mouse has petrified and stuffed the lion. Next Porky hires a gangster cat, but he leaves straight after a bonk on the head with a bowling ball.
Donald visits the "Museum of Modern Marvels" which showcases various futuristic electronic appliances and inventions. He uses a quarter on a line to get in (this allows him to keep his money and get in as well). Once inside, he is confronted with the "Robot Butler", a robot who takes hats ("Your hat, sir.") After Donald's hat is taken away from him, Donald uses a magic trick to produce another hat (similar to the way he produces flutes in The Band Concert). He says, "So!" and continues on his way. He first encounters a robotic hitch-hiker, which activates when he makes driving noises. However, when he laughs at it, it punches him in the face. Next he goes to the wrapping machine, which says "Do not touch" but Donald ignores the sign and hops on. When he pulls a lever, the machine proceeds to grab him in two robotic arms, put transparent wrapping paper around him, and put him in ribbons, like a package. He manages to break out by vigorously shaking, and continues exploring.
The Planet of Peril
The planet Mongo is on a collision course with Earth. Dr. Alexis Zarkov takes off in a rocket ship to Mongo, with Flash Gordon and Dale Arden as his assistants. They find that the planet is ruled by the cruel Emperor Ming, who lusts after Dale and sends Flash to fight in the arena. Ming's daughter, Princess Aura, tries to spare Flash's life.
Wolf, as the half-crazy assistant to Dr. Heller, an inventor of robots, murders his master, and attempts to take over the world with his death-ray equipped robots. He then proceeds to borrow industrial robots all over the world for high fees. "Baumann", a mining engineer and friend of Dr. Heller, then visits Wolf in his entranched laboratory of Heller's company and learns about his plan. Having witnessed the despair of his co-workers who lost their jobs due to being replaced by robots he explains to Wolf that the people will revolt when they lose their jobs en masse. Wolf however wants to crush down any revolts using his war machines and reach for world domination. He is then prevented from attaining this goal by Baumann and Dr. Heller's widow, as he gets killed by his own invention.