Factual error: In series 13, when phone numbers are referred to, they usually start 0808 (even mobile numbers). UK phone numbers starting with those numbers are freephone numbers and wouldn't be used for private use, or even for mobiles (which all start with 07).
Other mistake: The fire at the used cars dealership recycles several shots from the petrol station fire in Series 6 episode 7. These include shots of burning petrol on the ground and a Renault car with the registration mark B649 CLY exploding.