In the second Sunday's meetings, the hymn numbers posted on the sign in the background refer to those sung the previous week.
Near the end of the film, when Terry is cleaning his disassembled pistol, he inserts a cleaning rod into the muzzle (front) end of the barrel. That's incorrect. Proper cleaning procedure dictates that the brush should be inserted into the back of the barrel (the chamber). This prevents the rod from damaging the rifling located just inside the muzzle.
After Wes deputizes Stu and gives him a badge, Stu doesn't wear it for the rest of the movie.