In this episode, when Spock and McCoy are fighting the gladiators in a live TV studio which is broadcasting the combat, one of the producers has the line, "Fight, you two. You bring this network's ratings down, Flavius, and we'll do a special on you."

Reading up a bit about the background of this episode, I learnt that this was intended to be a satirical reference to the fact that at the time of production Star Trek's ratings were doing poorly, and it was widely rumoured that the NBC network was thinking of cancelling the series. William Shatner himself assumed the series would be cancelled at the end of the second season. Although this rumour has never been confirmed, it spread widely enough to mobilise fans of the show to mount a massive letter writing campaign to request NBC not to cancel it. Whatever the executives may have been thinking, they agreed to renew it for a third season.

Given the quality of the third season compared to the first two... one may wonder if it was worth it.

Transcript

1
Captain's log, Stardate 4040.7. Traced wreckage of SS Beagle to planet 892-IV.
Uhura: Planetary civilisation. Radio broadcasts, and an ancient format known as "video".
Kirk: On screen!
2
TV broadcast: The recent slave uprising has been suppressed. And in sports, gladiators killed barbarian William B. Harrison in the arena.
McCoy: How barbaric!
Kirk: Yes, black and white TV.
3
Spock: William B. Harrison was Beagle's flight officer.
Kirk: Allons-y!
4
{a cave on the planet}
Caption: Captured as soon as they beam down!
Septimus: We're escaped slaves. We are Children of the Sun.
Kirk: I need to find Captain Merik.
Septimus: Merikus? He is First Citizen!
Kirk: A name coincidence? Good enough for me!
5
{a Roman building}
Caption: Captured as soon as they enter the city!
Kirk: Captain Merik.
Merik: Jim Kirk. This is Proconsul Claudius Marcus. He knows we're aliens.
Claudius Marcus: Our Rome has conquered the whole world! Except for one Gaulish village.
6
{a prison cell}
Spock: Fascinating. The Roman Empire, with 20th century technology.
Kirk: A perfect parallel of Earth.
Spock: Yes. These Romans even speak English.
7
{a TV studio set up for gladiatorial combat}
Claudius Marcus: Order your entire crew down so I can force them to fight in the arena. Or else... I'll just force these two to fight in the arena!
Caption: Great ultimatum.
8
{Spock and McCoy in fight with two gladiators}
Spock: Do you need help, Doctor?
McCoy: No, I can flail a sword as ineffectively as any actor!
9
Claudius Marcus: Well, threats didn't work, so I'll have my beautiful slave girl seduce you.
Kirk: That won't work eith-! Wait...
10
Caption: Dissolve to Kirk waking up some hours later...
Kirk: Still won't work, Claudius!
Kirk: Care to try it again?
11
Caption: Scotty arranges a timely blackout!
Merik: I repent for no obvious reason! Here's your communicator so you can beam up.
SFX: stab!! {Claudius stabs Merik}
Merik: Aaargh!
12
{Enterprise bridge}
Uhura: Unlike you, beaming down completely unprepared, I've been monitoring radio for the past day. The slaves don't worship the sun in the sky. It's the Son of God.
Kirk: Holy misunderstandings!
Spock: Indeed.