The caves where the Children of the Sun hide out are one of the most-used locations in television and movies. In addition to being the entrance to Batman (1966)'s Batcave, they are also seen in Invasion of the Body Snatchers, Kung Fu (1972) and various police and western shows. They are located right below the famous Hollywood sign.
One of several "parallel Earth" plots in the series, contrived to save money by avoiding the necessity for "alien" sets, costumes, and makeup.
The episode parodies the television industry in several ways. Fake applause and catcalls are used to simulate a studio audience, and the race for high television ratings is lampooned several times. The TV station manager threatens the now-pacifist runaway slave that he had better fight convincingly: "You bring this network's ratings down, Flavius, and we'll do a special on you!" Later, the Proconsul sneers at Kirk about the captain's impending death, to be televised from the arena, by telling Kirk that "You're centuries beyond anything as crude as, television." Kirk replies, "I've heard it was... similar," an oblique reference to the series' own ratings difficulties. Comic relief is in the scene where McCoy and Spock heckle each other on the TV Stage during the gladiatorial duels.
The title "Bread and circuses" is a translation of "Panem et circenses", an ancient Roman metaphor for people choosing food and fun over freedom. It first appears around AD 100 in the Satires of Juvenal, which also provided the title of another Star Trek production about 20 years later: Who Watches the Watchers (1989).