Biker films were very popular in the 60's, even becoming a minor movie genre. Bruce Dern, who was making his 5th appearance on the show, had just been in one of those movies, "The Wild Angels". Here he's the head of a gang that rescues Kimble form the police. But he has an ulterior motive. He wants Kimble to kill someone- a guy who called the police on them after a robbery, the father of a fellow gang member who agreed to take the blame for the robbery and then took a deal, (you could do that at the time) to do military service instead of jail time and wound up in Viet Nam, where he was badly wounded, (we never see this character but "there's not much left of him"). Dern wants Kimble to perform the deed because he's already been convicted of murder and "they can only kill him once".
Diana Hyland and Lou Antonio play gang members, each making their third appearances. The guy they want to do is played by veteran character actor Crahan Denton, (this is also his fifth appearance), who died of a heart attack two days before this episode was broadcast. He plays a very frightened man, who might not survive just being harassed by the bikers as they buzz around him with their bikes. You wonder what his family must have felt as they watched those scenes.