After the shooting, there's a camera shot from inside a car looking down the street. The FBI car is now facing down the street with its bullet-riddled rear window towards the camera while two gunmen, who in previous shots hadn't gotten out of their car, are now running back to it. However, it's now parked facing the opposite way to which it was previously going.
Only three agents fired at John Dillinger, not the six as depicted in this film, and they only fired a total of six shots.
When the FBI men have put gangster Frank Nash in a car, other gangsters drive past firing machine guns. A man in the back of the FBI car puts his hands to his face as if hit, but it's not until afterward that bullet appears in the window.
The car is parked at right angles to the road when the gangsters with a machine gun in the front firing straight out of the door window. The bullets would only have hit the parked car in the rear not in the side where the bullet holes appear.