Audio problem: When the deer are all grunting at Rachel and Aidan, the whistle of an elk can be heard despite the fact there are no elk in the scene. (00:30:40)
Audio problem: In the flashback when Evelyn is walking into the small water fountain with baby Samara, the baby is heard screaming and crying unhappily. Yet when we see the baby's face her mouth is barely open and she doesn't look like she's crying. (01:07:30)
Answer: The deer were attacking the car because Aiden was in the car. Aiden was possed by Samara at the time and Samara makes animals go crazy.