Revealing mistake: In the episode when ACO Bulstrode is looking at the newspaper cut-out of the appliance crash (the one that Bayleaf was involved in), look closely at the cut-out. The whole article consists of the same paragraph written twice. Seemed the producers were too lazy to write a full article, hoping no-one would notice.
Episode #9.4 - S9-E4
Revealing mistake: The flashover in the disused factory's ventilation duct (where the pop video is being shot) craftily borrows a shot of the flashover in the laser arcade shout from Series 7 episode 5. The arcade's overhead walkway and the icon of the woman holding the laser gun is visible.
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.
Revealing mistake: During the flat fire, the girl tosses her baby to ADO Coleman. Just before he catches it, you can see that the falling baby is a doll.
Revealing mistake: Obvious CGI flames were used during the science lab fire, because when the teacher knocks over the Bunsen burner onto the flammable liquids, parts of the workbench instantly catch fire that were nowhere near the liquids.
Revealing mistake: In the episode when the schizo falls off the crane, the car he falls on explodes a split second before he actually lands on it.
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.
Revealing mistake: The shout where the paedophile's car gets petrol-bombed was done using CGI. The flames are not consistent between shots and there is no smoke whatsoever.