Gaffes

The young kid was shot in the right leg and had the bullet removed and a bandage applied. The next scene with the kid, his left leg has the bandage on it.

At 28 minutes when Hickok 's Jailer is in jail, Hickok put his boots up on the desk and his boots had rubber treads. Boots had leather soles in the nineteenth century.

At the beginning of the movie the soldier calls him Bill. His real name was James and he was never known as Wild Bill until after the Civil War.

In the opening battle scene, the Confederates are using a Gatling gun. Unless they had captured one, the Confederate armies did not possess any Gatling guns. Even the Union Army only used a few that were privately purchased.

The movie was shot in Santa Clarita, CA which was supposed to represent Abilene Kansas, where there are plains and flat grassland. No scrub brush and no mountains. If they wanted to stay in CA for costs at least use farmland/grassland in Ventura, Sacramento or central CA. Its just hard to watch when they say old west and most everything that was considered west at that time was the plains states, mountains and the desert southwest. At least Costner shot on location and Hickock died in South Dakota. It's not a documentary but there are shooting locations that are better than what they used.

As you see the train crossing a ravine, the camera shot pans over the bridge. A the bottom of the ravine you can see silage rolls in white plastic covers lined along the waterway.

Contrails can be seen in the sky at the opening of the 2nd scene.