I'm pretty sure the developers at Blizzard liked Snowpiercer a lot, because one of the new dungeons in the upcoming expansion will be something similar. Most of the time we'll be fighting on a huge, moving train of the Iron Horde.
Gnomes had submarines in Warcraft II, there's the Gunship Battle in the Icecrown Citadel raid, and don't forget the Deeprun Tram that connects Ironforge and Stormwind City. So a technologically advanced giant orcish train fits just right in.
This 5-man dungeon is called Grimrail Depot, and an early version of it is already playable in Warlords of Draenor's beta. Here's Fatboss and their team fighting through the whole thing. Hopefully the novelty won't wear off after a few runs, because this looks really cool.
And here's a different runthrough by AdriaCraft:
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