Under goofs, the Imdb critique referred to the fact that what is now southeastern Oklahoma doesn't look anything like the scenery in the movie (which was filmed in Ouray County, Colorado). However, what Ouray County does look like is John Wayne country, which I guess trumps geographical accuracy (no pun intended).
share... the scenery in the movie (which was filmed in Ouray County, Colorado)The location page only shows that the courthouse was in Ouray. A lot of those mountains are in the Sierras west of Bishop and Mammoth Lakes, CA as well as various Colorado locations. Those Oklahoma hills were never as majestic as in this film!
Possibly because the movie was based on a novel. Possibly the screenwriters felt that it was more important to specify the locations described in the novel than to change the names to wherever the movie would eventually be filmed which they might not have known.
A novel as a movie source is sort of like historical events as a move source. If you are planning to film a movie about World War II in California, are you going to change the dialog to make it war between Sacramento and San Francisco on one side and Los Angeles and San Jose on the other, to fit with the scenery, or are you going to Keep it a war between the UK, the USA, and the USSR on one side and Germany, Italy, and Japan on the other?