Trivia: Jack causes the Clock Tower to light up. At the end, the writer wanted someone to say 'Jack, did you remember to turn off Big Ben?' then have a bomb land on the Houses of Parliament and the Clock Tower. (The Houses of Parliament did get bombed. The joke was to make it all Jack's fault).
Trivia: At the undertaker's, the Doctor remarks on the strange behaviour of the gas light and Charles Dickens says "What the Shakespeare is going on?" This is a joke on Dickens' name, the expression "What the dickens...?" being a euphemism for "What the devil...?", making out that the phrase wasn't in use in Dickens' time and came from his name. In fact, "What the dickens...?" is much older than Dickens himself and has been in use since the sixteenth century, according to the Oxford English Dictionary.paolog
Trivia: The 2018 novelization, also written by Russell T Davies, expands the scene where conspiracy theorist Clive shows Rose pictures of the Doctor in multiple time periods. In the episode, he only shows her pictures of Nine, but in the book, he has pictures of every incarnation of the Doctor up to Thirteen, as well as pictures of two incarnations from even further in the future. The two potential future incarnations are described as a "tall, bald black woman wielding a flaming sword" and a "girl or boy in a high-tech wheelchair accompanied by what appeared to be a robot dog". Conveniently, Rose happens to turn away just as Clive shows a picture of the Tenth Doctor, since she can't see him before the regeneration in "The Parting of the Ways". On a final, amusing note, the picture of Thirteen shows her being chased by a giant frog outside Buckingham Palace.
Trivia: There is a scene where several of the robot spiders are scrambling through ducts, and one of them bumps into the camera, despite the robots being CGI. This is a reference to a legendary blooper in the First Doctor serial "The Web Planet", where one of the Zarbi - large, ant-like aliens - bumped into the camera.