Goin' South (1978)

Synopsis
Sentenced to hang in a backwater western town, horse thief Henry Moon (Jack Nicholson) is saved when frontierswoman Julia Tate (Mary Steenburgen) agrees to marry him. Taking advantage of the town law that prohibits the execution of married men, Moon follows Tate back to her ranch, planning all the while to escape at the first possible opportunity. But Tate insists that he honor his end of the bargain at work on the ranch. She has no intention of consummating the union, a fact that drives the hot-to-trot Moon up a wall. She puts him to work on the gold mine that she has on her property, while his old gang prepares to relieve the couple of their gold once it's on the surface. Jack Nicholson personally selected movie newcomer Mary Steenburgen for Goin' South. The film also features John Belushi in the role of a dyspeptic deputy. ~ Hal Erickson, All Movie Guide