Ok, 2 episodes in and i've already got some picky points.
First is, after 6 years, you'd think all the avalanches that could have been set off would have been, barring earthquakes. It's not as if there could be new blizzards-- at -118 degrees, the amount of water in Earth's atmosphere should be about the same as Mars's. I suppose there might still be windstorms, but none was shown. Not to mention, the snow should be a rock hard mass.
Next, they never stop the train, so how could they do maintenance on the tracks? What happens when a rail comes loose?
And they don't have armored shutters to cover the lovely full wall windows-- stupid. I assume, eventually the staff from another cattle car will salvage the carcasses. Including the human ones-- i think part of the long term plan is to make maximum use of the meat supply. Sure, most of the executive staff is horrified about cannibalism, but some are quietly pragmatic.
Anther thing, they keep referring to *the* engine. Or perhaps it's Engine, since they sometimes deify it. Only one? I've seen quite a few freight trains of our time with multiple engines, include some at the rear. That makes more sense, especially if you can't stop, and apparently one engine is not enought to keep full consumer electricity going and power through a snowdrift. With multiple engines you could stop one and service it, while another takes over. Assuming we're talking about Trident sub style nuclear plants, you're going to need about a week to cool down anyway.
And why a train, anyway? Why not a fixed bunker? The need to move increases the number of points of failure.
And how naive are the first class passengers, acting as if this is just another cruise? They don't seem to realize that they have no power anymore. Their money is spent, they funded this shiny big train, but that's done. It's the executive class that's in charge, and any onepercenter who can't actually help out is just another deferred source of protein. You'd think some of them could figure that out.
Finally, what is the end game here? Wait for a new geologic era to come, hundreds of generations in the future? That would be another reason to have a stationary survival plan-- reopen the coal mines, and bring back carbon dioxide and global warming.
That being said i'm going to keep watching for now.