Patzer

The entire plan to save the train relies on Zavarov & co. not knowing their arrival time, being away from Russia for the first time. There is no way they don't know. Tickets with seat reservations (like international tickets all passengers have on this train) show scheduled departure and arrival times.

The train line from Budapest to Vienna runs on electricity, not on diesel like in the movie. It has a set of electric cables above it. Hte helicopter couldn't have approached it like in the movie, and if someone climbs on the top of a train on this line, like Béci does in the movie, he would instantly die.

The train line from Budapest to Vienna runs on electricity, not on diesel like in the movie. Also, it has two track, not one. The totals with the train were shot on a secondary railway line in Hungary.

Trains arriving to Budapest from South-West cannot reach "Nyugati" railway station without slow and complicated maneuvers including two changes in direction. So in practice this approach is not possible.

The entire plan to save the train relies on Zavarov & co. not knowing their arrival time, being away from Russia for the first time. However, if they know their departure time, they obviously checked the timetable. Timetables show arrival times as well.