Corrected entry: Poirot is reading A Tale of Two Cities, at a table with a cup of coffee. Johnny Depp comes over and puts some cake down. Shortly afterwards a jug and a glass of water appear on the table from nowhere and remain there for the rest of the scene. (00:55:00 - 00:56:00)
Corrected entry: The train is constantly shown as being on a single track. There is no track for any trains travelling in the opposite direction. So, if the Orient Express meets a train coming in the opposite direction... the terminus in Istanbul has several lines running into it and its inconceivable that no other train is making its journey towards the city.
Correction: It is not that uncommon to have a single track railroad, even today Belgrade-Bar railroad has a single track part of the way. There'll be sidings, switches, signals, sections of double track, etc. to ensure safety.
Correction: The water pitcher and glass are there in the wide shot before Depp joins him.