After Matthew picks up his daughter from ice skating, she is in the back seat of the truck. When the truck is departing the parking lot, there is nothing visible in the bed of the pickup. In the very next shot, we are viewing the daughter as she looks out of the back window. In that shot there is a large, dark, rectangular shape in the pickup's bed that we can see in the reflection. The immediate scene after is a shot from inside the vehicle looking backwards toward the daughter, but you can also see out the back window and there is nothing at all visible in the bed.The large rectangular 'box' seen in the window's reflection was obviously a 'hide'. The use of this hide was to have a place to put the camera, and to create a 'non-reflective' area on the window to allow for shooting the scene from the outside-in.