Factual error: The problem with firing a cannon on steam power is to have the boiling water build enough pressure inside the barrel, with no leaks or openings to release it before its time. The professor's scarf and the plug hammered into the fuse hole (which also flies off just before the shot) wouldn't be good enough as pressure restrainers.
Revealing mistake: It is obvious that the night scenes were filmed in broad daylight, since clear shadows are still cast on any available surface.
Trivia: It was during the casting tryouts for the movie that Polanski and Tate first met; they got married about two years later.
Count Von Krolock: A year ago exactly on this same night we were assembled here in this very room: I your pastor, and you my beloved flock. With hopefulness in my heart I told you then that with Lucifer's aid we might look forward to a more succulent occasion. Cast back your minds. There we were, gathered together, gloomy and despondent, around a single meager woodcutter.