This episode introduces Festus Haggen (Ken Curtis) as a regular. This episode is also unique because it features all of the major characters, including Chester and Quint.
Ken Curtis appeared in 306 episodes, which beats Dennis Weaver's 290 by 16. However, he wasn't Festus in 5 of the 306.
This is the only episode in which Festus appears without a beard (although he does start out with one).
One of two episodes to feature both Festus and Chester.