Other mistake: The skull they used for the little girl in the well is obviously an adult's skull.
Other mistake: When Samara is falling down the well and we see the approaching water surface from her POV, there is a reflection of Anna looking down the well but no reflection of Samara.
Chosen answer: She says "Daddy loves the horses...but he doesn't know" meaning she knows what's about to happen to all his horses. (Because she makes them commit suicide).