Between minutes 16 and 18, when Dieter comes to visit Walter with a beer in his hand, the content of the bottle changes several times. When he puts the beer on the table, the upper part of the bottle is empty. When he picks it up, it's full again. He keeps it in his hand while the camera goes from one person to another, and at the next camera turn the bottle top is empty again. When he leaves the room, the bottle in his hand is full.