After Philip's car accident, it's obvious that his black Lincoln has been switched to another vehicle. The wheel covers are missing and the whitewall tires are now blackwall tires; Lincoln's in the '50s and '60s were never sold with blackwall tires, although they could have been changed by the owner.
When Beatrice Bartel (Jan Sterling) steps out of the car of her lover John O'Brien (Phillip Reed) into the heavy rain to return to her house, the scarf on her head and coat when she gets home look dry.
When Peter Harding is making the lethal drink for Philip Bartel in the hospital, the "water" in the glass had the powder in it before the poison was put in. The liquid in the glass wasn't clear.