Goofs

In the scene where Josh LaHood aims his rifle at the preacher and Club knocks the rifle aside, Josh drops the rifle about two feet from the steps. When the Preacher throws the dynamite and Josh runs off, the rifle is lying on the steps. Shortly thereafter, the rifle is about three feet from the steps.

When Hull drives off in his cart after visiting town and being saved from a beating by the Preacher, a modern white bandage and finger splint can be seen on Hull's left hand. It disappears in later shots.

When Stockburn's deputies confront Spider Conway outside of LaHood's office, they fire 32 shots in the first volley. After Stockburn fires his sixth shot and Spider attempts to fire back, the deputies fire another 36 shots from the same revolvers without reloading.

When the Preacher throws a bucket of water over McGill to stop him lighting the wagon on fire, the amount of steam coming from McGill's clothes indicates it is obviously warm water, but the only water the Preacher could've gotten from outside was the cold water from the horse trough. The water also entirely misses the flaming match, which remains lit.

Unless the trough was topped up with hot water to prevent freezing.

After the preacher left, the men find a huge nugget in the dry river. The man holds it easily in one hand. A nugget of that size would weigh at least 30 kilos (66 pounds).

It's not pure gold. It is aggregate rock with gold veins. As mentioned by Gossage at 01:25:00.

When the preacher approaches Stockburn he unlocks his firearm to re-chamber it. The bullet chamber he chooses is visibly empty yet he locks it in place and kills Marshall Stockburn. However, this could be a deliberate choice by the filmmakers, in line with other suggestions that the Preacher is some kind of mystical character.

The stick of dynamite that Barret throws away after it is dropped by the Preacher explodes much too soon considering the length of the fuse still attached to it.

Some fuses burn faster than others.

The windows throughout the film are obviously pane glass. In small California mining towns in the mid-1800s, the windows would either be wave type glass or simply covered by wooden shutters.

Perhaps in general, but this rich, gold-mining town had a very rich benefactor and can afford better glass.

When the Preacher shoots Stockburn at the end of the movie the camera angle shows his back and you can see the bullet holes on the left side of his coat, when Stockburn is shown from the front the bullet holes are on the right side of his coat.

In the final showdown, Stockburn is shot several times by the Preacher. In the next shot, small rivulets of blood are shown running out of the bullet holes. Considering that Stockburn is wearing a trenchcoat over a suit, it's unlikely blood would just trickle out onto the coat like that - not to mention a gunshot wound would probably bleed a little more profusely.

It appears early in the movie during the dog burial and Clint riding through the woods that the trees have been wrapped in plastic, either to simulate snow or birch trees. When Megan is praying you can clearly see a tree with thick bark covered with white material.

The protective plate and charges simulating the bullets exiting the marshal's back are clearly visible under his coat.

Someone stops Megan from taking the horses and wagon after Preacher, saying it would kill the horses to drive them further. Yet five minutes later, she and Hull drive off to return to the cabin, which is a long way off, and no one says anything.