Something I just noticed..
When Emily first sees Charlie, he's stepping out of a cave in the woods.
When this scene is playing the first time, we don't actually see Charlie, we only see him in a flashback.
However, if you watch carefuly at that first scene, just when the shot is from inside the cave with the butterfly flying in,you can see Charlie's abscured (De Niro's) profile on the right, just for a second.
Kinda creepy when you notice it.