Duster is supposed to be Mark's colt. After this episode, we never see him again.
Johnny Gibbs age is given as 20 years old on the wanted poster. But throughout the story,
we hear of all his accomplishments. He was some sort of entertainer with a show. He was
apparently an accomplished rodeo rider. According to story-line and Lucas. If Mark received all
the buckles he'd won it would be a lot. And he spent time drifting. It's hard to imagine how a
man of only twenty years could have gotten all that done.
When Lucas is supposedly thrown from a horse. It looks more like he took a running dive and rolled a few times. The only horse without a rider is quite a ways away, behind another horse.
Not where he would be he had just thrown Lucas.
In the first 1 to 2 minutes of the program an automobile with the sun reflecting on the windshield can be seen as the vehicle motors down the highway in the far distance.
Regarding the previous comment about Johnny Gibbs' age: The poster is easier to read at about 9:46 when Lucas unfolds and reads it. At this point, one can see that the age given is 25.
Early in this episode (34 seconds) you can see a car driving by in the distance.