The creation of Tigilinus the cup-bearer was in fact a late addition to the scripts. Originally, the Doctor saved Nero from being poisoned by accidentally knocking over the Caesar's goblet.
This episode takes place in July 64.
This episode saw the first use of stock footage for a cliffhanger, in this case, a lion.
This is the second story in a row in which the Doctor is given a surprisingly physical fight sequence. In fact, his brawl with Ascaris recalls similar fights involving the Third Doctor, including the Doctor judo-flipping his opponent.