Other mistake: When Annie goes to get her car keys, notice she goes through the back yard and goes to the front of the house as if the garage is in the back yard, when we see the garage on the right side of the house.
Other mistake: At the beginning, when Michael is about to kill his sister, we see through his eyes. When his sister turns around to see him, she has to look way up, meaning that he would be very tall, when in fact, he is only 6 years old.
In the scene when Michael is carrying Annie's body into the house her head is on the left side of his body. After they show Tommy looking out the window they cut back to Michael and suddenly Annie's head is on the right side of his body.