Episode #6.3 - S6-E3
Revealing mistake: Just before the runaway car crashes through the car park wall, you can see the pre-cut area where it crashes through.
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.