Whilst reading out the list of items Parker has purchased recently, an item called a Dogon eye is mentioned. This is the same item that Eugene had in Random Shoes (2006).
Richard Briers returns to the Whoniverse as Henry Parker, two decades after playing the Caretaker in Paradise Towers: Part One (1987)/Paradise Towers: Part Two (1987)/Paradise Towers: Part Three (1987)/Paradise Towers: Part Four (1987).
When filming the scene with Henry Parker, Richard Briers and Burn Gorman would do nine-minute-long takes. An extended version of the scene can be seen in the Series 2 deleted scenes.