When Ralph inserts a sheet of paper into the typewriter, it is clearly crooked, but is perfectly aligned when he begins typing.
When Nora is falling down the staircase you can see the stunt double crawl forward on the landing to continue the fall down the second part of the stairs.
While the nurse was asking a paralyzed Mrs. Manson a question requiring a "yes" answer, Phyllis Thaxter flinches a nod of her head. You have to watch close for it.