Continuity mistake: After Norman dismisses Norma's suspicion about him going to "another business meeting" as childish, he heads for the door - the sunlight from outside is flagrant as he opens it. In the next scene, Norman is seen entering his car, in the same outfit, and it is night time. (00:28:15)
Continuity mistake: When Norman is in Madeleine's shop, he picks up a chocolate chip cookie. We see him bite it, and we get a good look at the cookie. Then he sees Madeleine and begins talking to her. That is not the same cookie he had, because all of a sudden it has a huge chocolate chip near the top now...when it didn't before.