Jack the Ripper: I shall tell you where we are. We're in the darkest region of the human brain, a radiant abyss where men go to find themselves.
Netley: I don't understand, sir.
Jack the Ripper: Hell, Netley. We are in hell.
The first time we see the young doctor doing his "lobotomy" in London Hospital (to the girl that was married to Prince Edward), Ian Holm comments on the procedure for some guest as they stand behind a glass window. You can clearly see the young doctor doing the third strike with his hammer in a reflection in the window. The movie cuts back to the young doctor and he is doing the third strike for a second time.
When the Ripper is talking to his driver in the apartment, it's actually Ian Holm's voice, he just talking really low.