geography
Stagecoach 1966 seems to have typical inaccurate movie geography. The driver says he makes the trips back and fourth from Deadwood to Cheyenne.
According to the maps Deadwood, South Dakota is about 160 miles from Cheyenne, Wyoming, as the crow flies and not as the trail winds. I think that would be too long a distance to travel in the time of the story. And Mrs. Mallory is already in the coach when it arrives in the town where the other passengers get in to go to Cheyenne. Therefore the town at the beginning can not be Deadwood, South Dakota but somewhere between Deadwood and Cheyenne, Wyoming.
(10-29-2017 . Seeing the movie again recently, I think the banker said they got on at Dry Fork. There is a Dry Fork Mine in Gillette, Wyoming, but that looks too far out of the way to be on a stage line from Deadwood to Cheyenne.)
At the first stage stop when they discuss going on to Cheyenne Ringo says it is less than 30 miles to Cheyenne, and I think Doc Boone says that the long trip back (to the fictional Dry Fork) would be too dangerous for Mr. Peacock's health, implying that the they are more than halfway from the original town (the fictional Dry Fork) to Cheyenne.
So I guess that the original town (the fictional Dry Fork) should be about 60 to 80 miles north of Cheyenne, Wyoming. Since Captain Mallory tells a soldier to take the two dead soldiers back to "the fort" from the original town (the fictional Dry Fork), the original town (the fictional Dry Fork) could be near Fort Laramie and probably about 60 to 80 miles north of Cheyenne.
This is working fine so far. but what is Mrs. Mallory doing coming south from the direction of Deadwood trying to reach her husband stationed in southern Wyoming, possibly at Fort Laramie?
Did she say she came from her home in the east? If so she should taken the Union Pacific railroad from her home and got off at a station in southeastern Wyoming, like Cheyenne, and taken a stagecoach north to Fort Laramie.
So maybe Captain Mallory was stationed at Camp Sturgis, established in August 1876 in the Black Hills of South Dakota, or Fort Meade that replaced it in 1878. Maybe Mallory's unit was reassigned to Fort Laramie or somewhere near and he rode away with it, and Mrs. Mallory stayed to pack up their things and have them shipped by a freighting company and then rode to Deadwood and got on the southbound stage there, hoping to get off when she reached her husband's position.
So this makes a bit of sense. But most of it is my interpretation of what is said to make it as plausible as possible. Anyone who is halfway cynical will wonder if the creators of the movie visualized the geography that realistically.
Anyway, I wonder what natives of southeastern Wyoming think of the landscapes seen in Stagecoach 1966 that was filmed in Colorado. It is probably more mountainous than that part of Wyoming.