Deliberate mistake: After dropping Rick off at the set, we see Cliff driving his car back to the house to fix the antenna. View forward from inside the car, the rearview mirror is obviously missing. The next scene, outside with the car coming toward you, the rearview mirror magically reappears.
Deliberate mistake: The "CPR doll" smashed through the car's windshield, knocking out two-thirds or more of the glass. The doll would not weigh enough to break through the windshield (and maybe not even cause a hairline crack). The excessive amount of glass smashed out and the distance the doll flew before landing on the highway were obviously exaggerated for dramatic and comedic purposes. (00:47:00)