Both Gently and Baccus are seen using a police radio in their cars, but neither of them display an antenna which, in those days, would have been clearly visible.
When Gently and Bacchus go looking for Hazel Joyce, the camera pans across to follow Bacchus from the car to the seafront. As it does so, a modern car (a Vauxhall Nova) is seen parked in a side road.