At the end of the movie when the Indians are crossing over the river towards the cavalry before the explosions, there are several Indians seen briefly on foot. When the cross back over the river moments later, there are no Indians on foot. They are all on horseback.
None of locations remotely resemble any portion of path of the real Rogue River. Vegetation and topography of the real area depicted are totally different.
Since Oregon was admitted to the Union in 1859, this movie was set before the civil war. However, all of the troopers are wearing 1872 issue cavalry uniforms, not civil war era uniforms.
During one of the battles (at 00:59:00) in the background there is a power (utility) pole visible in the upper left corner of the screen.