At the culmination, Larkin shoots Cobb in the left arm. Cobb's injury is so bad that the cannot use it to assist in his reloading of his revolver. Moments later, after Larkin has been killed, Cobb uses that same badly injured arm to help lift himself off the ground.
When Larkin has his bullet wound treated in the boarding house, his shirt is covered in blood. Once he is bandaged, the same shirt is clean and good as new with no sign of a bullet hole. EDIT: Earlier, when Larkin was led upstairs by Evelyn, he is clearly carrying a folded shirt in his left hand which he picks up off the table when he goes to follow her. She obviously replaced his shirt with the clean one after bandaging his wound.
When his gang puts Drew into a rocking chair for his wake, it is right after his death. His legs are stiff and sticking out from the chair causing the chair to rock forward. If rigor mortis has set in, then how did his gang bend him into a sitting position to get him into the chair. But not enough time has passed from his killing for rigor mortis to have occurred. He still should have been limp. Further his head is fully erect instead of leaning off to one side. Then later in the wake his legs are naturally bent as sits normally in the chair. So, during the course of filming, sometimes the body had rigor mortis and other times the actor found time to relax and settled into the chair.
When one of the bad guys' horses drags him through and out of town, the rope securing the actor is clearly seen. Further, the actor is a good five feet behind the horse. This is so far behind the horse that clearly the bad guy has not had his boot/spur caught in the stirrup, which is what is supposed to have happened in the story.
Cobb's revolver has been altered. Cobb's revolver appears to be a Single Action Army as it quite obviously has a side mounted ejector rod. But when Cobb goes to load and reload his revolver he swings the cylinder out to the side, ejecting spent shells and then loads new cartridges. The Single Action Army could not do this. It had a side gate, which when flipped open, allowed the ejector rod mounted along side of the barrel, to remove spent cartridge shells. Once emptied of spent cartridge shells, new cartridges could be loaded, followed by closing the side gate. Revolvers either have the side mounted ejector rod and side gate or a cylinder that swings out. Revolvers do NOT have both systems. Cobb's does.
At the culmination, Larkin shoots Cobb in the left arm. Cobb's injury is so bad that he cannot use it to assist in reloading his revolver. Yet, there is NO blood. At least his leg wound bleeds.
When leaving the church service that was held in the general store, as Johnny Cobb bids farewell to the preacher, the boom mike is visible in the store's door window.