When Hélène first enters the hotel room where she will see the chess game, she unlocks the door and puts the keys back in her apron pocket. But when she enters the room, the keys are still in the door.
The first chess game between Hélène and Kröger is not logically possible. The opening three moves are those of a conventional Scotch Game. Then, between White's fourth move and Black's fourth move, the pieces rearrange themselves on the board, allowing Black to checkmate White.
The first morning when she's preparing to leave the house, Helene makes a tight chignon of her hair. When she's outside the hotel room, her chignon is much larger. Then, as soon as she enters the hotel room, her chignon is small again.
When Helene and Kroeger were playing their blind game. Kroeger calls for a move of j6, which is no such square. Obviously the person who translated the subtitles misunderstood plus doesn't know chess.
Boom mic is visible when Dr. Kröger and Hélène are sitting on his couch.