Bud Cort/Stacy Keach-TravelingExecutioner2 (1970)

Take me to the fields of Ambrosia ......

Bud Cort as Jimmy
Stacy Keach as Jonas

From IMDB :
Factual Errors or Goofs! -
An important plot point is the existence of a portable electric chair which makes the career of "traveling executioner" possible. Unfortunately, as shown in the movie, it can't work. To perform an execution Keach "starts" a big electric generator in his horse-drawn van. But the generator has no power source! At the time the story takes place the internal combustion engine was new and rudimentary. The only transportable source of mechanical power was the steam engine. There were no diesel powered generators. Of course a steam engine large enough to produce the necessary mechanical power to turn the electric generator would have been almost as large as the van and would have required hours to build up enough steam to do the job. Also, a substantial amount of coal to make the steam would be needed. In any case, no motive power is shown and this explains why there were likely no traveling electrocutionists. Why a remote prison would not simply hang convicted criminals is likewise not explained.

*Stacy Keach also appeared with Bud Cort in Brewster McCloud.