The more exciting horse scenes involving Mason are obviously performed by Wayne's stunt-double, Yakima Canutt.
After Gabby Hayes is arrested, Wayne rides out Hayes' ranch and encounters Hayes' granddaughter who has arrived there from school without notice. Wayne shows her to front door of the ranch house, gets back on his horse and rides all the way back to town again. There is no reason why Wayne went to Hayes' ranch in the first place.
At the scene of the robbery, the sheriff pronounces the banker dead but later in the film, the suspect is charged with 'attempted murder' and the townsfolk are told that the banker is expected to recover.