The motorcycle cop's motorcycle is knocked over but, in subsequent shots, is standing up again.
When they turn themselves in at the end, an extra is seen walking out of the building twice.
When Kaufman is lighting the corpse on fire the hippy turns away and returns to the car and is seen with his hand leaning on the car. Next shot shows the hippy still walking towards the car.
In the clip showing the hearse knocking over the cop's motorcycle, it can be seen that the motorcycle is already badly damaged.
When they are taking off after hitting the cop's motorcycle, you can see the motorcycle cop throw his arms up in frustration through the back window of the car from a distance. Magically the cop's motorcycle is no longer there.
When Phil pulls back the sheet covering Gram's corpse in the hospital morgue, Gram's right eye visibly twitches.
When Kaufman and the Hippy drive to the airport, there is a modern model pick-up truck in the background parked off the road in the upper right hand part of the screen.
The police officer at the airport is carrying a tonfa instead of a billy club. These were not in use at that time and weren't introduced to most police forces until the 1980s.
The motorcycle cop in the desert is riding a Kawasaki 1000 Police Special. This would not have been manufactured in 1973.
As the hearse pulls away from the Joshua Tree Inn, Barbara comes out of the room and runs to her car; she gets in and closes the door; you see her lean to the right and reach with her right hand to turn the key in the ignition, after which she leans left and turns on the headlights with her left hand, as her right hand moves the column shift into drive; THEN you hear the sound of the car engine starting.