Most characters are credited with ranks that to not match their insignia in the show. For example, Chief Superintendent Cath McLean has Assistant Commissioner epaulettes, as does Neville Carter who is credited as a Detective Inspector.
John Fordham is credited as a DCI, but is called a DC in trial scene dialogue. In reality, Fordham was a DC.
In all episodes depicting the border between Switzerland and Liechtenstein, the exact same cars, but in different order, are shown crossing the border.
Handling of real gold bars requires some effort as they are heavy, about 12 kg. The mock-up bars are obviously much lighter as they are often handled and moved too easily.
Rank is displayed inconsistently in the credits. Some police characters, such as Carter, McLean and Fordham, have included it in their credit, while others, like Boyce, Brightwell and Jennings, do not.
The Ford Granada seen in the series was not introduced until 1985, and a Ford Orion (Mark 2) seen in the background wasn't introduced until 1986 - both several years after when the series is set.
The story takes place in 1983, but the racks in the warehouse scenes were not manufactured until 1994.