The car in which Leo and Nico finally escape has a license plate saying "E-NA 98", which is although a valid German plate also a reference to the production company and the year of release of the movie.
A lot of details hint to Cologne as the filming location, among others the license plate of the Health Inspector's Mercedes. Also, "Koelsch" beer is served in the pub "Pauls Eck". However, the Alfa Romeo of the undercover cops has Munich plates, the car of Nico's persuers is registered in Berlin, and the one the thugs sent after Leo use in Dortmund. In the final scene Leo, Nico, Fabian and Reza set off with a car registered in Essen.