After Tolstoy signs the letter, Bulgakov is seen with the buttons on the right side of his collar instead of the left. It appears the film has been flipped.
When Sofya is talking to Vladimir about the new will, the right side of her face varies from being in and out of a shadow between shots.
Early in the film one of the characters refers to "flashbulbs," when there was no such thing in 1910 and in fact later in the film photographers are shown using trays of flash powder.
When Sofya is looking into Leo Tolstoy's diary it is written in modern Russian orthography which was not used at that time.
After the coffin has come out of the train station, a woman is seen solemnly crossing herself, left to right in the Catholic manner, not the right to left as the Orthodox.