When Jon is driving the truck full of dynamite to a safe place to explode, Ponch starts following and several other vehicles are seen on the road. In the next shot, from in front of the truck, there are no other vehicles.
When the members of the nude female volleyball team are looking back at Ponch and Jon following their (the team's) van, there is a shot through an angled rear window, yet the van pictured has a more or less vertical rear window that is covered by floral curtains. The shot of Ponch and Jon was filmed from a totally different vehicle.
When the student driver is driving, the driving instructor tells him to try a faster lane. Then she says "Good, very good.," implying that he has successfully moved to a faster lane. However, then the shot changes to their point of view from inside the car and they are in the right lane next to the side of the road where Leonard has easy access to throw dirt on their windshield. If they had just moved to a faster lane, they would not have been at the side of the road.
Right after Leonard throws a dirt clod at the student-driver car, there is no dirt on the windshield, yet in a subsequent shot taken from inside the car, dirt is visible near one of the windshield wiper blades. In the very next shot from the outside, the dirt is gone again.
When Jon calls in an accident, he says it's on the "westbound Glendale," but the Glendale Freeway (CA-2) runs north-south, not east-west.
Just before the student-driver car goes up the embankment, its driver-side door is shown ajar, but in the next shot from inside the car, the door is closed, and the very nervous student driver doesn't seem worried about the door. There's no reason a door would open by itself before a crash the way it is pictured.
Just after the truck explodes, as Jon and Ponch are fleeing on Ponch's motorcycle together, a cable can be seen behind the motorcycle which causes it to stop abruptly and crash, causing Jon and Ponch to fly off.