 In the scene where Chris (Vin Diesel) and Seth (Giovanni Ribissi)  are waiting outside Gregs (Nicky Katte) house, we never see the car  move or get turned on. Before they shot the scene Ben Affleck was  sitting in the car, listening to music. He accidentally took the car  keys home with him. They absolutely had to shoot the scene that  night and couldnt find Ben. They shot the scene with the car where  it is and lit up the house so there wouldnt be a reflection of the  camera and crew.