During the stampede, the shadows of the cattle as well as the shadows of the chuck wagon and its horses are short, suggesting that the light source (ostensibly, the moon) is high in the sky. But immediately after Owen stops the stampede, the shadow of the rocks he runs to is long, suggesting that the "moon" is low in the sky. Then in the chase scene that immediately follows, the shadows are short again. These scenes were obviously filmed at different times of day/night.
Rep fires 8 shots from a six shooter.
The inside ranch house light casts shadows of the window frame onto the outside wall and shadow of a tree or branch is cast on the front wall which is too strong to be from moonlight.Every thing gives the impression its night but when Laurie rides up it's light.
When Isham's men show up at the sheriff's office to get Owen, he escapes by going out the back door. It doesn't seem likely that no one would have been sent to cover the back door.
When Nan takes the pan of water off the fire to wash the coffee mugs, the water isn't even steaming.