In the scene just after Wendy has had her premonition, she comes back to the roller coaster worker waving his hand in front of her camera, and the picture of her sister on the coaster is never taken outside of her premoniton. If the picture was never taken, then how did Wendy have the picture later on in the movie so that she could realize that it was her sister in front of Erin and her friend on the coaster?