There are several hair changes on Dragonetti during the film. The film was shot over three years so it was impossible to have the same haircut during the production.
If you look closely you can see three 666s on the car number plate during the kidnap scene of Dragonetti. In Die Zombiejaeger had a taxi the same number plate.
The official soundtrack theme "Killer" is performed by the still photographer Patrik Skoglöw's band Mercury Monkeys.
It was specially written for Dragonetti The Ruthless Contract Killer.