There only seem to be one or two wagons when the Mormons are fleeing Kirtland. In reality there were between 1500 and 2000 Mormons who had settled in and around Kirtland. This substantial influx, combined with Mormon cooperative economics and bloc voting, was the main reason that gentiles in Kirtland feared the Mormons and ultimately forced them out.
The mob is depicted as attacking Joseph Smith for adultery and breaking his marriage vows. The mob was actually motivated by fear of Mormon economic and political power.
The opening shot shows the Mount Timpanogos temple in American Fork, Utah; but construction didn't begin on this building until 1993, years after this story takes place.