The Fall of Centauri Prime (2) - S5-E18
Corrected entry: Throughout this and the previous episode, Centauri's Regent mispronounces the name of his own planet as "Centuri." Only as he's dying does he finally correctly call his homeworld "Centauri." (00:15:05)
Correction: Londo has stated that there are regional accents with the Centauri (north and south). Plus the Regent was somewhat not himself, remember.