Snowpiercer
Great movie and I've enjoyed the series also. Haven't had a chance to read the graphic novel, but it's on my list.
The one thing I might change is when they stick the arm out and it freezes for 7 minutes and then they shatter it. If they did the whole 7 minutes but then pulled the arm in and it wasn't quite frozen solid and confuses the lady in charge because usually it only took 7 minutes, but this time it's not frozen and they actually have to stick the arm back out to freeze it more so they can shatter it.
I think this would have been a great hint that it is getting warmer outside and things are changing.