The position of Judith's arms change after she sits on the kid's toy in the kitchen.
In the scene where the children are all taking Pat's picture, the boy with the cape is first wearing pastel blue knee socks. It the next shot his socks have mysteriously changed to white knee socks with black stripes at the top.
In the movie's beginning, a can of air freshener goes off in the car. The driver's side window is partially opened. Then, when Pat goes to open the window, it is suddenly completely closed.
When Concepcion is being distracted during the abduction of Pat, cigarette smoke can be seen drifting into frame several times. Neither she nor the man at the door is smoking. It must come from the camera crew.
At the movie's ending, a television shows the 'final moments' of Pat before she disappeared. This is footage from earlier in the movie, shown from cinematic angles. This footage would not exist.