After the boat starts to float away, Marie has the gun with her, but the bag was left in the boat. As she's running through the woods, she's shown in various shots and angles, the gun is no longer with her.
After Marie rows across the river and starts walking, the boat started to float away. The first shot shows the front of the boat (pointed end) toward Marie, moving backward. The second shot shows the boat moving forward with the rear facing Marie. Then the last shot of the boat shows the front pointing toward Marie again moving backward.
When Marie and Nicolai enter a room for discussion, she places a box in front of the door after closing it. After the discussion, Nicolai goes to the door and opens it, but the box is not there.
When Nikolai digs a knife into his leg to remove a bullet, what he actually removes is the shell casing that wouldn't have left the gun.
It's clear from the plant life and the mountains surrounding the farm, that the film is not set in Russia.
The initial scenes reveal Sofia, the capital of Bulgaria, although the heroine confirms she has arrived in Russia.
When we see the family around the table in the opening scene, the daughter crossed herself with her left hand.