Episode #4.9 - S4-E9
Revealing mistake: In a scene in the mess, Sicknote walks in front of the television and there are grey stickers stuck to the screen to hide the production spotlights.
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.