Several people have challenged the idea that Gnosticism is obscure, and a case can certainly be made that it has never been more popular. But stand outside of any mainstream Christian church and ask the people filing out if they know what Gnosticism is and I'm pretty certain you'd get more blank stares than answers. That's what I mean by obscure.
But Gnosticism has certainly been a theme of many films in the last dozen years, including The Matrix trilogy, Dark City, and The Truman Show, to name just a few. Director Bong Joon-ho may not have made the film explicitly to convey Gnostic themes, but they emerge again and again throughout the film, and the Christian symbolism is even a bit heavy-handed (a bloody hole in the hand is never subtle).
Because of the space requirements I couldn't explore many of the interesting allusions—how the hallucinogenic drug kronole, for instance, served as a metaphor for the religious use of entheogens, or how the progress through the Snowpiercer train mirrored an occultist's mastery of the elements. Maybe I'll get to that in a more extended essay, but in the meantime, feel free to chime in with your comments.