There's a gross and unforgivable error with the trains in the background. At the beginning we clearly saw a pair of Central Trains class 170s. But the episode is supposed to be set in 2012, and as everyone should know, Central Trains is due to be abolished next year. The presence of a First Great Western HST and a Wales and Borders 158 probably gives away the fact that it was filmed in Cardiff even though it was set in Essex.Our entertainment business is at least that careless.
THE TARDIS IS QUIRKY. Where Worlds Collide notes liberties taken with Dr. Who's future transportation.