Continuity mistake: Watch the bar scene about ten minutes from the start of the film. The barmaid is holding 2 pints, but note how the froth disappears when the shot changes as they are placed on the bar.
Continuity mistake: When the potato truck with Rusk searching the woman's dead body for his R lapel pin is traveling on the highway, the tailgate is down which allows potatoes to fall out. As the police car passes the truck, the tailgate is up. When the truck driver stops to check the tailgate, the tailgate is again down.
Continuity mistake: The amount of fish soup the inspector has in his plate changes between shots. The contents of the plate also change and sometimes we see different fish.