Why do they have flying cars?

In the episode of "Mean Streets" Walker is in a vehicle chasing bad guys in a car down the city streets at night. The bad guys are heading into an intersection where their light is red and traffic is crossing. A pickup crosses and is hauling a trailer. You can see there's going to be a terrific accident when, suddenly, the camera switches to the view from the opposite side of the intersection and now the bad guys car is somehow airborne and ends up going over the trailer and speeds away! How come they had flying cars in 1993 but not now? :) In the shot showing their car about to collide with the pickup, you can clearly see there is nothing in the street that would cause the vehicle to rise upwards. Why do television shows back then and now still make it seem as if autos can become airborne for no reason?