Mister Croup says that the Tang Dynasty figurine was made by Kai Lung. Kai Lung is, in fact, a fictional ancient Chinese storyteller in a series of humorous and satirical books by Ernest Bramah, published between 1900 and 1940.
Much of the filming took place on the London Underground in long abandoned tunnels and the post office railway that were used to deliver mail across the capital. British Museum and Down street were once used at genuine stations, the underground contains about 50 closed stations.