Harsher in Hindsight: Poirot (who's a suspect in the case) claims that the day he commits a murder, it certainly won't involve blowpipes and poison. When he does commit a murder in Curtain, it involves shooting a sleeping sociopath at point-blank range.
Values Dissonance: The narration casually mentions that Jane Grey and Norman Gale both "disliked loud voices, noisy restaurants and negroes" (the latter part is removed in some editions). This is not intended to make them seem unsympathetic in any way.
