While Laura is sleeping there is a tree branch hitting the window. There is no tree in the front of the house.
At 35:12 Laura is in the back of the cart pulled by the horse. When the camera shows the horse drawn cart from the front there is a wood railing behind Laura at waist level. After the cart goes past and they show the shot from the back of the cart, the railing is gone.
After Laura breaks the music box, the pitch of the sound it makes fluctuates up and down indicating that it is broken. However, this would not happen with a real music box.
When Laura is trying to fix the music box, the wooden handled screwdriver rolls off the table and falls but there is no sound.