Other mistake: Early in the film, Valerie Barksdale (Hilary Swank) visits Annie Wilson (Cate Blanchett) for a psychic reading. Valerie has been severely beaten by her husband, and her badly black and blue eye is swollen shut. A day or two later she visits Annie again. Amazingly her eye appears to have completely healed, even though the other marks on her face are still visible.
Other mistake: When Buddy has his father tied up in the backyard, he has a strap in his hand and starts to whip Annie with it when she goes near him. He tells her to get away, that's what we hear, but when he is lashing out at her his mouth is open and he doesn't mouth anything.
Answer: The TV in Annie's room.
The TV wasn't on before, and Annie is suspicious of the noise and light, which she wouldn't be if it was just the TV.