• At the Harmony Shoal press conference, Brock tells the assembled reporters that “Any questions after today can be handled by Miss Shuster or Miss Siegel” – some relation, surely, to Superman creators Joe Shuster (1914-92) and Jerry Siegel (1914-96)?
• When Nardole rescues the Doctor from the point of Mr Brock’s gun by materialising the TARDIS around him, he says he made a few “accidental stop-offs along the way” – including 12th-century Constantinople, where he claims to have “ruled firmly, but wisely”. If we’re to take Nardole at his word, he most likely took the place of one of the Emperors of the Komnenid Dynasty: the military leader Alexios I (Byzantine Emperor from 1081 to 1118); or his son, John II (1118-43), known as ‘John the Good’; or John’s son, the extravagant Manuel I (1143-80).