When Kenet crashes the car, initially as seen from the bridge, he takes out sections of wooden fencing right up to the bridge's superstructure. However, in the shot from below, two sections of the fence before the bridge remain intact.
After Kenet kidnaps the doctor, they stop in a diner and he orders two hamburgers before they make a call from the phone booth. He then pays and leaves without the hamburgers. Although no one in the diner says anything, they likely presumed the two left due to an emergency, not complaining because the bill was paid.
(at around 9 mins) A group of doctors is looking at Kenet's skull X-rays. The X-rays are hung behind the illuminated frosted glass panels, so viewers can see the X-rays, but the doctors could not. And the X-ray as the viewer sees it is oriented correctly to show a left-side hematoma, but to the doctors, the X-ray is reversed, meaning the hematoma would be on the right.
At the gas station, the "rain" is clearly coming down straight (no wind) from two separate angles. In wide shots, the lines of "rain" can be seen reflecting on the pavement with gaps between them.
Mr. Kenet had brain surgery while in the psychiatric hospital, but shortly thereafter he has a full head of hair. His head would have been partially shaved for the surgery, and his hair could not have grown back in less than three weeks. This time line of three weeks is confirmed when Mr. Whitcombe enters the elevator in his office building, Mr. Cronner, the janitor/elevator operator, mentions the murder of Whitcomb's secretary and says that it happened the night he got sick and said he had been sick for just over three weeks.