Early on in the film Pat shoots at a police car with a pump action shotgun and the engine blows up disabling the car. Being the owner of said pump action firearms this is actually impossible to do especially at that distance.
In the red light district, an adult store advertises movies on VHS and DVDs. DVDs were not available in Britain until the late 90s.
When Sam talks to Josh on a terrace in Southend, Sam is wearing a pair of Tom Ford sunglasses. The movie is set in the 90's & Tom Ford's first sunglasses range was not released until 2005,