During the initial race, one of the times they switch to the in-car view, yellow marker lines are seen, as on a public road. There are no other cars so apparently this is the lead car they are showing. When they switch back to the group view looking back at the lead pack the road is the race course, wider and with no yellow line markers in view.
During the shootout in the parking garage, Mannix obviously returns fire through the rear window of his car. When he backs out of his parking spot in pursuit, there are no bullet holes in his car or windshield. Also the outside, driver's side rear view mirror, hit by the 1st shot, appears to be intact. As Mannix leaves the parking garage, there are multiple bullet holes in the windshield.
The race car driven by Ed Kovak appears to be a Formula Vee since the wheels have a large diameter, 5-bolt pattern used on early Volkswagen Beetles. After the crash and later when Mac Wagner is performing a failure investigation, the wheels have a small diameter, 5-bolt pattern and the wheels appear to be from a 1960's era GM automobile.
When Ellen Novak first goes to talk to Mannix, the close-up on both actors reveals a very obvious, thick beige stripe painted down the bridge of both their noses. It's some five shades paler than the rest of their dark-brown noses, and isn't blended in, so that, on modern televisions, it appears sorely obvious. As the P.O.V. cuts from Mannix to Ellen, the stripe is off and on more subdued, with its edges blended in, meaning there were touch-ups in between takes, and later the editor picked and chose what he spliced together.
This is the famous "burning hay bales, exploding car" clip used in the beginning montage. But in a frame-by-frame analysis, as viewed from the road on top, nothing is burning as the car goes though the hay bales. As viewed from below, the car, not yet burning, goes flying over the embankment, followed by two burning bales of hay. Then the car explodes, starting from under the front. The car did not set the hay bales on fire, nor did they start the car on fire.
The character portrayed by Sabrina Scharf is consistently referred to as Maureen. In the closing cast credits, her character name is listed as Marie.