Area code "416" for Happy Valley would put the lodge in or near Toronto, Canada.
In the scene in the dungeon with Johann, Herman and Grandpa, a man wearing a mask was used instead of having two Fred Gwynnes.
Herman tells Grandpa that he's going to see Dr. Frankenstein in order to give him a progress report on Johann. When Herman returns from the visit, however, he enters his house with a newspaper and lunchbox, as though he has just returned from a day at work.
Dr. Frankenstein IV (to Johann): If you don't behave, I shall take out your brain and put it in backwards.