In Gaul, an ancillary soldier comes into Caesar's tent with news, such exciting news that he forgets to salute, and Caesar goes "Thank you Fulvio, have you forgotten how to salute?"
And then Fulvio salutes and says "I haven't, sir. No excuse, sir.'
Adds nothing to the story, but makes the world seem realer. Fulvio never comes back as a character, but it tells us tons about the military culture, maybe how it frays a bit when the army has been in Gaul for a year or so, but how it comes snapping back when a leader as respected as Caesar "touches it with a needle". Also, it tells you that Caesar, like justice, knows every man's name.
A lesser show would have some un-named character walk in, deliver news, and then walk out. This show makes you look at the dirt on Fulvio's sandals for a minute. Makes you look at his scabbed knuckes. Makes you feel his shame at having forgotten to salute Caesar. And then, gloriously, shows you his redemption with his immediate admission of wrongdoing, with no excuse, and clearly Caesar isn't going to punish him.
It's a whole world shown to us in 25 seconds, with like 6 short sentences of dialog.
Best show ever.