In Series 2 Episode 4, whilst in the car Gerry says to Sandra and Jack that the last time Brian went to the cinema was to see Ben Hur. However, in this episode, Brian tells Esther that he went to see Lawrence of Arabia with his friend. (Lawrence of Arabia was brought out in 1962 and Ben Hur was brought out in 1959.)
UCOS are having lunch and decide to go visit the house directly from there. But when they arrive the wall clock in the house reads 10:30.
Maddox incorrectly attributes the line "Déjà vu all over again" to Sam Goldwyn.
It was in fact baseball player Yogi Berra.
Gerrard's Cross, where murder victim David Snaith lived, and Pinewood Studios, where his body is discovered, are both in Buckinghamshire, which is policed by the Thames Valley Police NOT the Metropolitan Police. Their authority only covers Greater London.
When the team are watching another of the Internet clips, Gerry makes a comment about knowing about bondage etc. The clip then continues and as it ends, there is a view of a clapper-board. The intention was that this was the clapper-board for the original black & white film they are watching. Unfortunately the text on the clapper-board reads "New Tricks.... " with a filming date of January 2009.