The Night of the Tartar - S2-E19
Revealing mistake: When West opens the wall safe in the personal train, there is no locking mechanism shown on the opened door. Without this, the door of the safe could just be opened without rotating the combination lock on the outside. (00:01:50)
The Night of the Tartar - S2-E19
Other mistake: As the coach is entering the courtyard, Count Sazanov and Anastasia are standing side-by-side. In the space between them, one can see by the gate's entrance, a car driving from right to left. (00:22:15)