The barber shop, which comes and goes in the corner of the building next to Matt's office, is a sewing and mending shop in this episode.
A couple episodes prior to this one, Festus had a special way of swinging his arm to toss horseshoes so that he would get a ringer every time. In this episode, he just gives it a regular toss.
Posters for the variety show are being hung up all over town, but later scenes of people moving around the streets don't show any posters.
Matt sees the dwarf, Billy, nailing up a flyer on a post outside the office window, and Billy's head is almost up to the top of the bottom window. When Matt goes outside, the Billy is much lower, even while standing on a chair.
When the carnival arrives, the calliope player is rendering "Over the Waves" (written in 1888) and "The Billboard March" (written in 1901). The latter is impossible, and the former highly unlikely, as Dodge was in decline in the early 1880s.
Dodge seems completely deserted, with everyone down at the show, but the number of people at the show is a lot less than the people seen in town on a regular evening.