During the standoff, Mr. Rockford is standing in front of a police car with its lights on in one scene, off in the next, and on again.
When the LAPD cruisers are using lights and sirens on the way to the hospital, the first shot shows a a 1974 Ford Galaxie with two of the 'can' lights on the roof. Then the next shot shows a 1975 Plymouth Fury with two rotating gumball lights and then the third scene has the squad car has morphed into being a 1973 AMC Matador with the twin gumball lights. In 1973, they still were using the 'can' lights on the Matador.
About halfway through in a scene involving the Cadillac limo, you can see the rear door panel has been matted so that crew and lighting aren't reflected during dialogue. The quarter panel behind the door is regular finish, much shinier paint.
After the brakes on T.T.'s truck are sabotaged, Muellard and his thugs are watching from the right shoulder of the road. However, the truck travels quite a ways down the mountain road before it crashes, along the way showing a steep hill going up along their right, making it impossible for the spectators to view the crash. It's edited to make it seem as though the crash happened just past Muellard and company.