There was a (reasonably recent) Doctor Who episode that had a “train in space”. I’d long since stopped watching by that point, but according to Google it was basically “Murder on the Orient Express”. In space.

Maybe — drawing direct inspiration from the opening to “The Hitchhiker’s Guide to the Galaxy” — the story revolves around the destruction of Earth to make way for a new hyperspace train line. The whole thing could be a thinly veiled commentary on HS2 and the proposed demolition of that housing estate in Mexborough. I can see it now — the in-movie campaign would promise to “Save you up to TWO WHOLE LIGHT DAYS on your journey across the Milky Way.”