Downing used the same "Red River D" brand used by Thomas Dunson(John Wayne) in Red River.
As Cruze is riding back with one of the outlaws, he's arrested; tracks of a large earth-moving vehicle are visible at the bottom of the frame in one shot. Such vehicles didn't exist in the days of the Old West.
Dorothy Malone's hair and wearing men's clothing are anachronisms.
Wrong names are used.
At the climax, after Marshal Cruze engages in a standoff with the Moran brothers, he subdues and seemingly handcuffs Hort Moran. Hort is not present with the group of criminals as they are being taken back in town for incarceration.
Tray is the only one captured. Hort and Gad were both killed.
In the closing credits Robert J. Wilke is listed as "Hort Moran" and Douglas Kennedy is listed as "Gad Moran," but in the film Wilke is portraying "Gad" and Kennedy is "Hort."