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.
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.