Continuity mistake: The teenage girl in the first house they sleep over in hands Bruce Willis a mug of tea the following morning. First it shows her front and his back, and she turns the mug so the handle faces him as he takes it. Then it cuts to facing him from behind her, and the mug handle is now facing away from him.
Continuity mistake: When Harvey finally gets his opportunity to pick up the hitchhiker, she approaches his car and stands at the driver's side. At one point, the camera is on Harvey, and to the left, you can see her reflection in the car's shiny paint job and she is smiling. When the camera cuts to her, she isn't.