The name of the presiding judge, written on the wall of the building behind Roy and Chon when they are about to be hanged, is "Moriarty" - a nod to the Associate Producer Bruce Moriarty.
Chon Wang is the Chinese translation/pronunciation of John Wayne. However, in the case of Jackie Chan's character, Chon represents his last name while Wang is his first name. This represents the order Chinese names are presented.
A sign is visible during one of the Carson City scenes during the latter part of the picture showing the words 'Bulldog Drummond's'. He was a fictional British detective that first appeared in a 1920 novel, almost forty years after the movie's setting in 1881.
When the horse carriage knocks over the hanging gallows, Roy falls to the wagon below. Before he falls, his hands are tied behind his back; as he falls, you can see a piece of rope tied around each hand, which are separated (when he places his hands together, this gives the appearance that his hands are tied together).