During the opening sequence, while Louise is wandering the streets of Los Angeles, her shoes change from pumps to sling-backs and back again.
When Louise and Carol are at the piano recital, David and his friends can be seen in the distant background approaching their seats. When it cuts to a medium shot of David, they are approaching their seats for a second time.
When Louise and Dean grab the stair banister of their townhouse on their return from the lake house, the banister shakes much more than such a solid looking structure would in reality.
When Dr. Willard (Stanley Ridges) finishes his interrogation of Louise (Joan Crawford), he finds Louise's husband, Dean Graham (Raymond Massey) waiting in his office, after being telegraphed that Louise was at Los Angeles Municipal Hospital, where Ridges has been questioning her. Graham would have been in Washington D.C. when he got the wire and would not have been able to fly out to Los Angeles that quickly.
When Louise is brought into the hospital, Dr. Willard examines her and says to another doctor that she's "beautiful, intelligent, and frustrated." However, she's in a coma, so he has no way of knowing if she's intelligent or frustrated.