As for the Agatha Christie novel (films), you're right, all of you. The book has been printed at least with three, if not four different titles (not mentioned yet here: 'The nursery rhyme murders', very PC, more PC than 'And then there were none' for this also inevitably invokes the recall of that particular nursery rhyme; at least in Germany). The different movies based on the novel had different titles.
Here's perhaps more than you want to know about that novel.
When I was a kid it was PC in Germany to say "Neger" (negro) instead of "Schwarzer" ("black man"), we would have been corrected for using the wrong (offensive) word. The once wrong word became the good word in the seventies and the once good word became the wrong word. Since about ten years the new good word is "Afrikaner" (African) but you have to be very careful in using it for reasons pointed out first by K~~. Call a person with a dark skin colour "Afrikaner" and she isn't from Africa she'll resent and people from the North of Africa can get quite mad when they hear you using the word "Afrikaner" in the sense of sub-Saharean African, for they are also Africans though with quite a different colour of skin.
In most cases, "(s)he is an Antiguan", e.g., is the best choice, but when for some reason you want to refer to skin colour, isn't it best to name the colour instead of naming regions of the Earth not being perfectly correlated with what you want to say? And as for the choice of the colour term, English/German or Latin, I'll take the least offensive, whatever it is in the respective decade.