Set in a future 1970, the United States is considering building bases on the Moon. Colonel Briteis, Major Bill Moore, and Doctor Wernher are sent to orbit the Moon to survey landing sites for future lunar missions. However, Dr. Wernher is an impostor whose mission is to destroy the US's Earth-orbiting space station, which he plans to do by colliding the rocket with the station on the way back from the Moon. Colonel Briteis is arrogant, rash and distrusting of Major Moore. Moore, in turn had a romantic interest in Briteis when they began in the USSF, but was rejected in favor of her ambition to be the first person on the Moon. Moore realizes that the man claiming to be Wernher is actually a spy for an unnamed country, because the imposter has no knowledge of Werhner's trade nor the Brooklyn Dodgers baseball team. In the ensuing struggle for the control of the rocket, Col. Briteis accidentally hits the boosters, which saves their lives, but leaves them stranded. She takes unfair blame which Moore assures her is not her fault. Briteis then realizes, she may not have all the answers and does need help on the mission from Moore. They have to make an emergency landing on the Moon. With them all marooned, Dr. Wernher redeems himself by helping establish communications with Earth, although an accident results in his untimely death. In response to the unexpected turn of events, the US authorities decide to make the immobilized spaceship the core of a new moon base. Later, the General, called Pappy, has a heart to heart with Moore on his feelings about Briteis. Moore is insecure in her feelings as he states "she has no need for me." Briteis, overhearing this, later proposes to Moore via Papi and cuts a deal with Madame President to make Moore Brigadier General of Project Moonbase to make up for her earlier actions towards Moore.
Both Project Moonbase and Cat-Women of the Moon were made using some of the same sets and costumes. The two films were released within one day of each other, though from different distributors. Project Moonbase was shot during 10 days.
''Mystery Science Theater 3000''
Project Moonbase was featured in episode #109 of Mystery Science Theater 3000 along with Chapters 7 and 8 of Radar Men from the Moon, a Commando Cody serial. The episode debuted January 6, 1990, on the Comedy Channel. Kevin Murphy, who worked on the show and would become a cast member the next season, wrote, "The best thing I can say about it is that it was very very short," calling the film "openly and condescendingly hostile toward women as a gender". As with most first season episodes of Mystery Science Theater 3000, Project Moonbase is not considered one of the series' better efforts; it did not make their Top 100 list, as voted upon by MST3K Season 11 Kickstarter backers. Writer Jim Vogel ranked the episode #164. Vogel said, "There’s some glimmers of later-season MST3k goodness in there..." The MST3K version of Project Moonbase was included as part of the Mystery Science Theater 3000 Volume XX DVD collection, released by Shout! Factory in March 2011. The other episodes in the four-disc set include Master Ninja I, Master Ninja II, and The Magic Voyage of Sinbad.