When Jesicca stabs Devon, the glass shard that she used to kill Devon is still in her hands, also to be seen in Devon's neck.
In the scene where Ritchie wakes up at the morgue, the bodies are clearly breathing when he and Heather leave the room.
During moments when the graphic of the clouds moves above an out-door shot of the sanatorium, the clouds flow superimposed across the crest of the building much like the top of the building was see through.