When John and the fake Jack the Ripper talk during the book fair they mention a letter that Jack the Ripper sent to the police with a piece of human kidney. John says he didn't send the letter. That letter is in fact one that historians debate was the work of the real.Jack the Ripper, which some believe to be the work of a copycat.
When the lawyer Vanessa hired to get H.G. out of jail shows up with a passport for George Wells it shows a birthday of 1975. That would have made him 42. Freddie Stroma who plays him was 30.