this is interesting for a couple of reasons...

the streets were closed and in theory the cars are performing under a controled scripted environment so a police car taking a short cut through closed streets doesnt factor into the controled environment and the car "acting" shouldnt have to give way..

its kind of like someone walking infront of a filming camera and ruining the shot...

and then there is the police "barricades" surly they should of radioed through for everyone to stop the moment the car broke the shutdown streets

then there is always the possibility it is actually part of the movie