- Awesome Ego: Poirot constantly praises his own intelligence. Christie eventually came to find it annoying, but the fans didn't. He really is very smart, and he also says that his boasting serves to throw people off, because the English believe that "a fellow who thinks as much of himself as that cannot be worth much."
- Awesome Music: Invoked in "Yellow Iris", where the attempted murderer arranges for the performance of a superb singer (with the lights down) so they could go unnoticed while committing the crime.
- Complete Monster: ABC & Mr. X. See those pages for details.
- Critical Research Failure: In Death in the Clouds, it is said that a blowpipe is about a foot long, when in actuality it is six feet long, a mistake that Christie admitted. Ariadne Oliver also makes a reference to the research failure in a novel of hers in Mrs. McGinty's Dead.
- "Funny Aneurysm" Moment: The short story "The Kidnapped Prime Minister", set in 1919 and written in 1925, is about Poirot having to find the titular kidnapped Prime Minister before the Versailles negotiations start, because if he is not present then the treaty might be 'too lenient'. Of course in hindsight it's generally thought now that the harshness of the Versailles treaty played a major role in the rise of Adolf Hitler.
- Funny Moments: In a reference to Sherlock Holmes' adventure The Yellow Face, a story has Poirot request Hastings to do something similar to what Holmes asks Watson at the end of the story. Hastings ends up pulling out the warning minutes later.
- The Problem with Licensed Games: To a point. Metacritic has given the games based on the series mediocre reviews: Murder on the Orient Express was given a score of 60 out of 100 (though the only saving grace is having David Suchet of the Poirot TV series voice the titular character in spite of the fact that the protagonist you control is female); Evil Under the Sun was given scores of 66 for the PC version and 46 for the Wii version; and The ABC Murders was given a score of 53.
- Recycled Script: Some of Poirot's adventures are so good, other characters copy them. Done by Poirot himself in "The Plymouth Express" and "Mystery of the Blue Train".
- Values Dissonance: "The Augean Stables" sees Poirot go to great lengths to bury and discredit accusations of embezzlement by a former Prime Minister... which happen to be true. This obstruction of justice, which involves destroying a man's career, is considered right and proper in order to defend the late Prime Minister's reputation, prevent his party from suffering a great loss of face, and prevent a politician from another party from becoming the new Prime Minister (as he is considered to be most unsuitable for the position). Nowadays Poirot would be the villain in the story. Although to be fair, Poirot says he would not lift a finger were the politician still alive, and that Don't Shoot the Message is the only reason he's getting involved at all.
- Plus the accusations were being spread by a seedy tabloid newspaper, so it's not as if they were on the up and up either.
- Viewers in Mourning: Poirot received an obituary in the New York Times when he died.
- We're Still Relevant, Dammit!: Third Girl attempts to deal with Swinging London youth culture, to somewhat questionable effect.
YMMV / Hercule Poirot