The American distributor wanted to cut 20 minutes of dialog from the film. I suspect that many of those cuts would have come from the last act dialogs in order to streamline it into more of the action movie template implied by the American release poster. A dominant mode of action sci-fi uses the Big Idea of the premise to set up an escalating set of conflicts that are ultimately resolved with the big fight scene.
But Snowpiercer isn’t an action film. It’s a dystopian science fiction film in the old tradition of Planet of the Apes (the original) and Logan’s Run. It makes a number of decisions in the last act that support its Big Idea at the expense of cinematic formula.
The Big Idea for Snowpiercer serves a dual role as both allegory and frame for conflict. An attempt to curb global warming goes horribly wrong resulting in a snowball earth. Humanity survives on a train powered by an “eternal engine.” People who unimaginatively demand plausibility behind science fiction allegories can take comfort in the fact that this is a religious claim rather than a technical one. The tail section lives in impoverished squalor. Rich oligarchs live in the front section. And at the very front, the engine and its engineer, Willford. The train is a microcosm and allegory for a social system that is, to use a phrase that dominated the last economic crash, “too big to fail.”
Protagonist Curtis plans an ambiguous revolution to take over the train and negotiate a more equitable distribution of resources. He’s goaded by the old leader Gilliam, and his younger friend Edgar. Travel through the train involves peeling through layers of privilege presented through surreal set pieces. The violence see-saws dramatically between bizarre ritualistic behavior and brutal chaos.