When Dick is in his office pushing the car's remote control, he locks the doors, and the car chirps once. Later, when the Solomons enter their kitchen and Dick locks the doors with the remote, the car chirps twice.
The rear view mirror in Dick's rental car has clearly been removed.
When Dick is sitting in the car with Mary and Nina, the top of the studio wall can be seen reflected in the bonnet (UK)/hood (US) revealing this as a set.