In the initial scenes, the biker clearly has no sidearm when pulled over, then magically has one when he challenges the officer.
Instant explosion #1: DeeDee shoots the pickup truck with a shotgun.
Instant explosion #2: The motorcycle crashes into a parked car.
The officers are shown being killed immediately by the "silicone" bullets the gunman uses. Armor piercing bullets that can penetrate body armor are ineffective for killing people since they do not expand like normal bullets such as hollow points. Bullets other than armor piercing ones are designed to expand and thereby cause more damage.
When DeeDee tries to start the Chevy police car to pursue the gunman, the noise heard is that of a Chrysler engine.
The gunman uses the police radio to cancel the call. There are at least three problems with this as depicted. First, the officer's radio ID would not be publicly displayed- for example in Adam-12 (1968) nothing in the car said 1 Adam 12. Next, police dispatchers as well as other officers recognize the voices of officers, and all would realize it was not the traffic officer using the radio. Finally, the gunman assumed the officer had called in the stop.
No explanation for how the shooter knows where the targeted motorcycle cops will be, and when they'll be there in such a huge city.
Several characters make reference to silicone bullets in regards to penetrating police body armor. Silicone is a soft rubber like material that cannot penetrate anything. The proper term would be Teflon coated armor piercing bullets.
In the second officer shooting, the gunman is shown firing using a tinted visor at night. Under those conditions, he'd not be able to see the officer that was wearing a dark uniform to shoot him.
A character says the first officer killed never drew his gun, but when he was killed he had clearly drawn his revolver.
Hunter has the motorcycle cop crush out a cigarette and then puts both cigarettes into his pocket. This would contaminate the evidence.
Needlessly reckless for Hunter to leave McCall alone while she's breaking into the suspect's trailer.