When Matthews drives up to the dock the Ford he drives has roof lights which are flashing and the cowl vent is open. After he talks with the suspect and goes to leave the Ford he leaves in has steady burning roof lights, the cowl vent is closed, and it has a different model siren on the roof.
The mystery driver in the opening scene is driving a '39 or '40 Ford convertible. The shot of it going over the cliff is of a car from the late-1920s or early-1930s.
In an early scene . . . in the police station . . . the paper in the typewriter (being used) is noticeably crooked.