The Very Long Night of Londo Mollari - S5-E2
Corrected entry: When Doctor Franklin tells Sheridan about Londo, he says that the Centauri have a bipulminary system. The correct term would be bicardiary system. (Pulminary has to do with the lungs, cardiac/cardiary has to do with the heart.) (00:10:10 - 00:11:00)
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.
Correction: For the Centauri, their two hearts do everything our lungs and kidneys do. Londo refers the 'cardio respiratory system' when poisoning Refa.