The steering column in the Willys changes position several times, as does the steering wheel type.
When Sonny Munn blows up the Hemi motor in Brian Edison's Willys, Edison steals another Hemi out of Police Chief Marsden's AMC Matador patrol car. AMC never used Chrysler Hemis.
The final 1/4 mile drag race in the film takes an abysmally slow 35 - 40 seconds and a chute is still pulled by the winner. An average 4 cylinder economy car usually runs a 1/4 mile in 15 - 18 seconds.
In the first crash scene nether actor was wearing seat belts as with a crash like that would have possibly killed both actors.