When Peter goes to newspaper office to research decades-old murder of someone named Curtis, newspaper librarian looks up appropriate microfilm reel by victim's last name. In reality, all newspaper microfilms - a photographic record of all newspaper pages from a certain period - are filed by dates of newspaper recorded - not specific events.
When Peter describes his first dream, he tells his girlfriend that "she (Marsha) was hitting me in the (private parts) with a paddle. Initially, the director may have wanted to show the murder as involving an injury of this sort, because when the man in the dream falls back into the water, he is holding his private area. But, it is very clear that when he is in the boat, he is on his stomach. There is no way she could have hit the front of his body.
When Peter leaves the showroom where he sees the 1937 Cord, the motorcycle police escort for the driving scene is clearly visible in the mirrored windows of the buildings across the street.
As the camera pans in on Marcia, between 1:20:31 and 1:20:32, the shadow of the camera or other crew member is seen in the mirror.