The 90 minute theatrical film was the pilot for the television series Buck Rogers in the 25th Century (1979), but was shown in theaters several months before the series aired. The film made over $21 million in North America alone.
Originally, Twiki was just going to make unintelligible electronic noises (the "biddi-biddi-biddi" sound) and Dr. Theopolis was to act as his translator. However, this was deemed to be too similar to R2-D2 and C-3PO from Star Wars: Episode IV - A New Hope (1977) and so Twiki was given a voice of his own.
Why there are two different Tigermen in the original film? According to costume designer Jean-Pierre Dorleac, it's because the fight scene between Tigerman and Buck was added later, after the original production had already wrapped. When they tried to call the actor who had played Tigerman earlier in the film back (he had been "discovered" for the role on the Universal Studios back lot tour), they could not find him! So they had to replace him with a lookalike (frankly, who did not).
To cut costs, some footage and various props were used from Glen A. Larson's series Battlestar Galactica (1978). Even some of the concept designs from Galactica were used. The Terran starfighters on Buck Rogers were originally designed as the Colonial Vipers for Galactica, but Larson had opted for a design closer the X-Wing fighters from Star Wars: Episode IV - A New Hope (1977). Larson then employed the unused designs for Buck Rogers.
The Buck Rogers theme features lyrics that were not used for the television series. This has been noted that these lyrics seem to parallel plot developments in the later Buck Rogers-inspired series Farscape (1999).
To make Buck appear frozen in his space shuttle, he was sprayed all over with an ordinary dry shampoo. Because of this, he could not open his eyes or move, so while he was waiting for them to shoot the scene, he supposedly fell asleep.
Kane's backstory was that he was a former student of Doctor Huer's who defected to the Draconians and to act as consort/advisor for Princess Ardala, the chief antagonist of the series. In the original movie serial Buck Rogers (1939), "Killer Kane" (as he was known) is actually a powerful gangster from Earth and is the chief antagonist of the story. Princess Ardala was not featured in the 1939 movie serial.
Originally, Buck was to have been put on trial, found guilty and banished to Anarchia, along with Twiki and Theo, until Wilma comes looking for him with an idea that might prove his innocence. In the finished film, after reshoots, the story was restructured so that Buck chooses to explore Anarchia (with Twiki and Theo tagging along), until Wilma arrives to bring him back, then he's put on trial, found guilty and sentenced to be terminated, until Wilma presents him with the opportunity to prove his innocence. Since these changes came late in production, there were several tie-in publications released (including the novelization and comic adaptation) which followed the original sequence of events.
In the original ending for this film, Buck and Wilma celebrate the victory over Ardala and Kane by dancing to the tune of "Chicago, Chicago, that toddling town". This last scene was entirely cut and the film now ends with Buck and Wilma returning to Earth by starfighter.