Revealing mistake: In the scene when Dodge is knocking at the second house to see if Olivia is home, check out the top left corner of the screen during the shot of Penny sitting in the car - a bird flies by inside the car. The only reasonable explanation is that the visual effects team not only made the bird graphic visible through the window but also in front of the rest of the car. They might have forgotten to bring the car layer in front of the bird layer, causing a bird to be seen flying over top of the entire image.
Continuity mistake: In the scene where Dodge and Penny enters Olivia's last known residence, Penny one of the door windows. She then gets access to the door lock on the inside and she opens the door. As Penny and Dodge enters, it is visible that the window is broken. This is shown both in the first and second shot. At the third shot it is easily noticeable that the same window behind them has been magically repaired, and is in a normal, unbroken condition. The fourth shot shows that the window is again broken.