Gentleman Broncos is a love letter to science fiction, but it's not an articulate sonnet from a mature writer. It's the scribbled notes of a high school outcast. That is to say, it is definitely Napoleon Dynamite does sci-fi. The references are not specific impersonations in the Disaster Movie/Meet the Spartans mode. They're just vague, quirky acknowledgments that the filmmakers love everything connected to the genre.
Benjamin (Michael Angarano) writes science fiction stories. It's the only joy in a life of poverty with his mother, who struggles to make dresses and sell popcorn balls for extra cash. Benjamin gets to attend a writing camp with acclaimed sci-fi novelist Ronald Chevalier (Jemaine Clement), who ends up plagiarizing Benjamin's submission. Benjamin is stuck making VHS movies with the local film moguls, who don't do much better with the material than Chevalier.
From the opening credits, you can tell the filmmakers love this world. Each credit is printed on a sci-fi novel with cover art that suggests cheesy space battles in the enclosed text. Chevalier is famous for a series of cyborg harpie books that have been turned into movies. The harpies' weaponized armor suggests more sexualized sci-fi of the Barbarella era.
You see multiple versions of Benjamin's story visualized. In Benjamin's version, the hero Bronco (Sam Rockwell) is a long-haired, bushy-bearded space warrior fighting to recover his stolen gonads. In Chevalier's version, the hero Brutus (Rockwell again) is fey, with white hair and a moustache, in pink spandex. The townie filmmakers also do a cheesy version of Bronco with homemade props.
The Bronco sequences look like Star Trek: The Original Series with their painted soundstage backdrops. They're a little more sophisticated in coloring but just as fake-looking. There's stiff prosthetic makeup on the aliens, clunky wirework and animatronics that barely move.
The world surrounding the sci-fi is full of vague references too. At a Q&A, Chevalier fields obscure questions about his work and gives an irreverent take on answering a question that actually matters. At a book signing, he awaits gushing fans dressed as characters from his books and their film adaptations. He also shills a little merchandise.
In between, there's more of a standard quirky indie comedy. It all fits the Napoleon Dynamite tone, which is relishing the awkwardness of the kind of quirky characters Jared Hess likes to glorify.