At the start where Kevin and Winter are in the helicopter there are several times where Kevin and Winter switch places. That would be difficult since the helicopter was flying at the time. The footage was flipped left-to-right, which can be spotted as the headset microphones switch sides at the same time.
When Airwolf shoots down the black Bell UH-1J the exploding wreckage is a red and white MD500.
When Kevin is flying the Santini JetRanger the image goes from reversed to normal. Since it is thus reversed, the door on the right hand side goes from open to closed, and the clown who was on that side falls out even though the helicopter banked to the left.
After the police helicopter has been shot, the smoke generator is visible on the left skid before the helicopter lands. The smoke is not coming from the engine as it would be had it been shot in that area.
When Mr. Hansen is flying the Hughes helicopter and the Airwolf flies past the right hand side, he looks out the left hand window as if trying to see it there.
After Kevin flies away from the burning hangar in the police helicopter, the shadow of another helicopter (most likely the camera helicopter) is clearly visible as the police helicopter flies towards the bottom of the screen.
When Kevin catches up to the bad guys' black helicopter after they killed his Uncle Chester, the main bad guy is Jake who has blond hair and is not wearing sunglasses. The other two bad guys are also not wearing sunglasses. When the bad guy in the rear of the black helicopter opens fire, Jake is no longer seen nor is the original bad guy pilot but instead a man with dark hair wearing sunglasses.