Goofs

At 1:17:32, four panes of glass in the window are broken out, yet, 4 seconds later, when the same window is shown, 11 panes are broken.

The ruts on the hillside in front of the farm vary in depth throughout the film.

The sheriff dismounts his horse and takes a step towards the wounded man. His deputies are still in their saddles, on their horses. As the camera moves in closer, the sheriff is two steps in front of his horse and both his deputies are dismounted and standing holding their horses' reins.

When Henry is using the shotgun against the man under the house you hear two empty shotgun shells hit the ground. The sound made is of plastic hulled shotgun shells which didn't come about until 1960. Back then shotgun shells would have either been brass, or most likely, paper.

When Wyatt shoots and misses, he then holds the revolver with 2 hands clasped together in front of him for his next shot. This style of shooting is modern and no one in 1906 would try to shoot that way. The two-handed style of shooting was developed by George Cooper, in the 1950s, from techniques used by earlier experts. However, it had to evolve from somewhere and it is not possible to say how early it developed. It takes a strong hand to fire a powerful handgun and many people may have used two hands, to steady their aim.

The bird Kitchum carves is visibly bigger that the piece of wood he picks up from the ground at the start of the movie.

When the rifle is used during the opening sequence, it is clearly not aimed properly. The adjustable rear sight obviously did not line up with the front sight and, in fact, the gun was aimed into the ground and far below the target, resulting in an obviously careless take.

Contrail visible on sky at (1:23:50) when Henry runs from farm and is pursued by Ketchum.

Henry refers to tuberculosis by its modern name. However, in the 1800s, it was usually referred to as "consumption," despite the term "tuberculosis" having already been coined by Johann Schonlein in 1834.

The rifle that Tim Nelson uses in the final showdown is a Winchester Model '94, which is not inaccurate in 1906, but the version used in the movie is an Angle Eject Carbine version introduced in 1982. This can be seen in the configuration of the receiver top, seen in closer shots of Tim when he confronts the outlaw gang.