Red Sundown (1956) is a Universal-International Western starring Rory Calhoun, Martha Hyer and Dean Jagger. It was directed by Jack Arnold under the working title Decision At Durango. (Another one of those Universals with the “Print by Technicolor.”)
Came across some behind-the-scenes photo of the sheriff’s office set. Note the light and crew member on the right.
Now look at this still from the finished film, where the wall has been added behind Dean Jagger — or probably more likely, removed in the shot above.