The rear view mirror on the front windshield of Ellen's 1955 Ford Fairlane convertible is missing in some shots, but in place in others.
The amount of sun and clouds changes between shots when Bud and Dorie are on the roof of the tall building, with some shots needing obvious artificial lighting.
Near the end, Gordon is riding to the mine in a Cadillac limousine that has air conditioning, as indicated by small air scoops on both sides behind the back doors.
The next shots (after the accident) show a different Cadillac without them.
Cars of this era with factory installed air conditioning had half of the system in the trunk, requiring outside air via those little air scoops.
At the beginning of the film, where Dorie is crying on the bed, Bud goes over and turns on a small lamp on the dresser. The bright light streaming through the blinds in the window behind, spilling on to the far wall disappears - not instantly or all at once, but more slowly from right to left and finally in the window itself, as if a "barn door" or other shutter system was being closed on a light offstage.
After the garden party when Ellen says that she is going to bed as she's tired the shadows reveal the time to be very close to noon with the sun directly overhead.
After falling down several rows of bleachers, the pregnant Dorothy gets up and says she is fine. It is unthinkable that a pregnant woman would not worry that she might have a miscarriage.