Corrected entry: We are told that the entire track is about 140,000 km, and they traverse that in 1 year. This works out to about 16 kph, which is about 10 mph. On the outside views, they seem to be trying to show us a fast moving train.
Corrected entry: Although the man's arm is frozen completely solid in less than 15 minutes with exposure to the outside air, we know by the end of the movie that the earth is generally at a temperature of more than 32°, because areas have been melting.
Correction: The train is travelling incredibly fast. In doing so, it will travel through areas with different external temperatures. Just because some areas of the world have a temperature above 0°, does not mean there are not other, much colder places on the train's route.
Correction: The train travels 438,000 km a year, not 140,000, which is an average of 50 kph.
Bishop73