In order to save Colonel Brinkley from Fred Engel, one of the Colonel's tramps shoots at Engel from his six shooter. He shoots eight times without reloading.
The guitar played in an early saloon scene does not have any strings.
As the alleged driverless stagecoach enters the city, you can see that the reins, for the stuntman who is actually driving the carriage, lead into coach box.
When the tramps retreat from Buttler's farm, one of the "dead" bandits tries to get up too early and is kicked by a horse.
Around 14 minutes in, there's a bar scene in which one of the townsmen is wearing plastic framed glasses from the 1950s - 60s and a baseball cap. Neither would have existed when the movie took place.
As the tramps prepare to attack Butler's Farm, a Car passes very far in the background.
The mentioned butterfly Papilio polymnestor parinda is from Sri Lanka and not from North America.