As The Virginian, Trampas, and Hill (and Ryker, later in Season 1) ride their horses on the dirt road In the opening credits, tire tracks can clearly be seen.
John Grainger is introduced in season five as Elizabeth Grainger's grandfather. When John dies and Clay Grainger inherits Shiloh Ranch, he is identified as John Grainger's brother and, presumably, Elizabeth's granduncle. But by the time of a season seven episode, "Girl in the Shadows", the story has changed and Clay is the elder brother of Elizabeth's father which would make him John Grainger's son, not brother.
The setting of the show in Wyoming Territory in the 1890's would have resulted in a very short run of episodes since Wyoming Territory ceased to exist after July 10, 1890 when the State of Wyoming was admitted to the Union.