Directed by: Matt Reeves
Starring: Richard Jenkins, Chloe Grace Moretz, Kodi Smit-McPhee, Cara Buono
The Father: Maybe I want to get caught.
Owen: What are you? Really?
Abby: I just know that this is what happens when you don't invite me in.
The Policeman: What do you mean a little girl? How little?
The Policeman: Are you a Satanist? Are you involved in some sort of cult?
Abby: Help me.
The Father: Please don't see that boy again.
Factual error: A fire breaks out in the hospital due to one of Abby's victims being exposed to sunlight as she's turning into a vampire, destroying that vampire and a burning a nurse to death. Modern hospitals have fire sprinklers, fire extinguishers, etc. and sensors/alarms that the fire would have activated.
Chosen answer: The thing that zooms across the water appears to be Abby herself - upon breaking the window, she beheads the boy holding Owen under the water almost immediately after she enters the pool room; her incredible speed makes it possible that she moved rapidly over the water without sinking below it.
Purple_Girl
Its one of the bullies upside down you can see if you pause at the right time or slow it down.