From CHiPs Online:
When Ponch and Jon get Bonnie out of her cruiser, Jon has to remove her seat belt. Later, at the hospital, Ponch tells her CB partner and his mother that Bonnie would have been killed had she not worn her seat belt. However, when Bonnie is driving along before the accident, she's not wearing one at all...not even when she begins to swerve all over the place!
When Bonnie's car is found, the lights are sticking out from a hill. When we see the car crash, the lights stay on top.