Minnie: It's Doctor Pretorius. He says he wants to see the Master. Most insistent.
Henry Frankenstein: Pretorius?
Minnie: He's a very queer looking old gentleman, sir. I must see you on a secret, grave matter, he said. Tonight. Alone.
Henry Frankenstein: Bring him in.
Elizabeth: Henry, who is this man?
Minnie: Doctor Pretorius.
Minnie: Doctor Pretorius? Pretorius? - - Wha-wha-what, what was the name?
Doctor Pretorius: Doctor Pretorius.
Doctor Pretorius: Isn't it amazing, Henry? Lying here, within this skull, is an artificially developed human brain. Each cell, each convolution - ready. Waits for life to come.
Doctor Pretorius: Sometimes I have wondered whether life wouldn't be much more amusing if we were all devils, no nonsense about angels and being good.
Doctor Pretorius: Follow the lead of nature - or of God, if you like your Bible stories. Male and female created to them. Be fruitful and multiply. Create a race. A man-made race upon the face of the earth. Why not?
Henry Frankenstein: Oh, what a wonderful vision it was. I dreamed of being the first to give to the world - the secret that God is so jealous of: the formula for life. Think of the power - to create a man - and I did. I did it! I created a man - and who knows, in time, I could have trained him to do my will. I could have built a race. I might even have found the secret of eternal life.
Continuity mistake: At the end of the film the Monster tells Dr. Frankenstein, to leave. The Doctor and his fiancee run off. The Monster grabs a lever and says "We stay, we belong Dead." He pulls the lever which blows up the castle. If you look to the left on the screen as the ROOF is collapsing, you can see Dr. Frankenstein knocked out on the stairs. Seconds later they cut to the SAME Doctor and his fiancee running to safety OUTSIDE the castle. It turns out in the original ending Universal killed the doc, but it tested poorly with audiences. They probably wanted a happy ending so they did a new ending where the doc lived, but they could not afford to blow up that castle again.