When Gunvald is making a phone call with a mobile phone (with built-in camera) inside the castle - despite he could not have brought that phone inside the castle due to a metal detector at the front entrance. Later on, when Beck and the other police officers are trying to save Gunvald, they go there by car and can't alert Gunvald as he has told them in a previous phone call (from inside the castle) that he is unreachable and had to leave his mobile phone in his car due to a metal detector at the front entrance. When Beck and the police officers, who all are heavily armed, enters the castle - no alarm from a metal detector goes off. In other words, a lot of plot holes in the end of this movie...