During the second chase, the police car changes from a Dodge St. Regis (horizontal headlights) to a Dodge Monaco (vertical headlights). This was due to the footage being reused from Season 3 in The Cheerleader Murder (1983), to include the exact same crash.
When Corrigan and Stacy spin out in the initial pursuit, tire marks are present on the pavement from a prior take.
As is usually the case, Corrigan and Stacy blow the initial pursuit by crashing. However, all they did was spin out. There was nothing for them to hit, and accordingly no way for Stacy to be injured, and no way for their car to explode.
We're reminded again how the show served as an example of what not to do regarding police procedure. On the initial call, both cars have their overhead lights flashing upon arrival. Proper procedure is to arrive at such a call with no lights on at all. Next, all three officers approach the front door, at which point Hooker tells Corrigan and Stacy to cover the back. That decision would have been made before the approached the house, not ganged up in front of the door as was shown. Finally, at a call of this nature, a perimeter is established so the entry officer(s) can clear the home. Corrigan and Stacy violated the perimeter, allowing the suspects to escape.