Factual error: Throughout the episode there are sections of dialogue in Greek, which are deliberately left untranslated. The subtitles frequently transcribe the Greek inaccurately. For example, the Greek girl who assists Poirot and Lyall in finding out about the poison says "Elate!" to them, which means "Come!" said to more than one person, but this is transcribed in the subtitles as "Ella!", the form used to a single person. Later on, the girl's grandmother says "Ohi enas Anglos anthras. Mia Anglitha yineka. San esena" ("Not an Englishman. An Englishwoman. Like you"), but this is given in the subtitles as "Ohi enas Anglos anthras, che yenika. Son ethena", which doesn't make sense. (00:40:45)
Factual error: At the end of the report on the findings of the crime scene, the "Italian" inspector tells to his subordinates what literally would translate as "Removes this meddler from here, no more access to the prisoner, that you understand?", which is just wrong in accent, cadence and construct. (00:36:30)
Factual error: The mysterious venom used to perpetrate the murder comes according to the English coroner from a "Vilitilio Occius", said to be a horn viper. Nothing wrong with artistic liberties making up animal species, but the name itself appears to be pseudo-latin with no real meaning or any closeness to other snakes, so not a particularly believable one.
Factual error: When Poirot leaves customs with Mademoiselle Lyall, one of the supposed Italians asks in that language "What's happening, what is this noise?", which does not make sense in context, especially with the officer just shrugging and showing him the card. (00:32:55)