Abbott and Costello Go to Mars

Orville, the oldest orphan at the Hideaway Orphans Home, accidentally hides inside a truck headed to a top-secret laboratory. He is noticed and placed under the supervision of lab worker Lester to help load supplies for an experimental rocket. This unexpected misplacement launches the sequence of space-faring mishaps.

At the lab, Orville is kept under Lester's wing and tasked with helping load supplies onto the experimental rocket ship. He observes the crew's routines and becomes part of the flight preparations. The stage is set for a launch that will carry him far from home.

In a moment of mischief, Orville accidentally flips the ignition switch, sending the rocket roaring into space. Lester and Orville realize they are launched on a cross-country journey rather than remaining on Earth. The rocket climbs into the sky, dragging them toward an uncertain future.

The rocket lands outside New Orleans, where Mardi Gras is in full swing. Orville and Lester, stepping out in spacesuits, believe they have landed on Mars and begin exploring the festive city. They merge with grotesquely costumed revelers, unaware of the real situation.

Wearing their spacesuits, Orville and Lester roam the streets among the carnival crowds, mistaking the revelry for Martian activity. Their odd appearance attracts confused glances and comic misunderstandings. The misinterpretation sets the tone for the ensuing chaos.

Two escaped convicts, Harry the Horse and Mugsy, stumble upon the rocket and slip into spacesuits. They head into New Orleans with plans to rob a bank and steal clothes so they can blend in. Their arrival introduces real crime into the mistaken Martian misadventure.

Lester and Orville are wrongly accused of the crimes and flee back to the rocket ship for safety. Mugsy and Harry force them to launch again, demanding that their destination be Mars rather than Earth. The trio is pulled into a new, perilous voyage against their will.

Once in outer space, Lester and Orville manage to take control of the crooks' gun and steer the ship toward Earth. The dynamic becomes a struggle for control between the spacefaring foursome and their criminal companions. Their attempt to re-enter Earth marks a reversal in the mistaken mission.

Rather than returning home, the rocket crash-lands on Venus, where female guards seize the four men and bring them before Queen Allura. Venus is described as inhabited only by women, with men banished long ago. Allura quickly takes a liking to Orville, appointing him as the king consort on the condition that he stays true to her.

Orville agrees to Allura's terms and becomes her king consort, while Harry and Mugsy are imprisoned for their crimes. The arrangement creates tension as Orville navigates a new social structure on Venus. The others await their fate in captivity.

Mugsy has one of the female guards flirt with Orville to test his loyalty, hoping to expose him as untrustworthy. The ploy sows doubt in Queen Allura about Orville's true intentions. The Queen, angered by the test, decides to take decisive action.

Distrust deepens on Venus, and Queen Allura orders that all men leave the planet. The four men are forced to abandon Venus and seek a return to Earth. Their departure signals the end of the king consort arrangement and Venus's banishment of men.

The trio returns to Earth to a grateful parade, where the public celebrates what they believe is a Mars mission gone right. Allura watches the celebration from Venus, plotting from afar. The mistaken voyage becomes a civic spectacle and a comic victory.

From her vantage on Venus, Allura sends a spaceship to Earth that delivers a cake to Orville's head during the celebration. The gesture is playful and humiliating, underscoring Allura's lingering hold over the fate of the travelers. The film closes on this humorous, arc-like prank.