YMMV / Murder on the Orient Express

• Accidental Aesop:
  • Casseti's murder of Daisy had horrific consequences for much of her family: her mom in shock gave birth to a stillborn child and then died, her father killed himself in grief, and the maid killed herself when she was accused. The lesson is how our actions can damage others in ways we can't imagine.
  • If a total stranger offers you lots of money, walk away from them: even if they aren't lying about the payout, there are probably massive strings attached. Poirot walks away from Ratchett's offer of cash, sensing he was trouble. If he had taken Ratchett's money, he would've put himself in the crosshairs of almost a dozen vengeful people.
• Complete Monster: Ratchett/Cassetti is a murderer well-known to Hercule Poirot for his international notoriety. A blackmailer who kidnaps people, murdering them when the authorities close in but still collecting the ransoms, Cassetti was the murderer of a little girl named Daisy, having continued to exploit her family days or even weeks after he had already killed the girl. Uncaring of how this killed four innocent people, from Daisy's mother dying from grief in premature labor with her new baby, to her father's suicide and an innocent maid killing herself when she was falsely accused of complicity, Cassetti cares only for escaping justice and was so evil that even the heroic Poirot feels obliged to cover for his killers.
• Esoteric Happy Ending: Poirot tells the passengers he knows that they all had a hand in killing Casetti and how they did it, but ultimately goes along with Mr Bouc and Dr. Constatine's agreement that the first theory — a stranger having jumped onto the train, killed Cassetti and left — is what they will give to the police. The entire Armstrong household has spent a long time figuring out this act of revenge and comes off scot-free for killing a man, even if said man deserves it. The novel depicts this as a pretty happy and nonchalant ending. The adaptations went into the ethical question of whether this is or isn't a good idea. The 1974 film shows Poirot as being very reluctant to let the passengers off the hook, the Poirot version had Poirot suffering a severe Crisis of Faith, while the 2017 film has a similar crisis, and even plays it as a somber Pyrrhic Victory for the culprits, who are too traumatised to appreciate their "victory". The latter two versions also raised the question whether the conspirators would kill Poirot if he revealed the truth; the Poirot version had one suggesting it to be quickly shot down, while Poirot gave the conspirators a Kill Me Now, or Forever Stay Your Hand in the 2017 film.
• Funny Moments:
  • The utterly composed British valet testifies to reading a bodice-ripper.
    Poirot: And what, may I ask, are you reading?
    Masterman: At present, sir, I am reading Love's Captive, by Mrs. Arabella Richardson.
    Poirot: A good story?
    Masterman: I find it highly enjoyable, sir.
  • Dr. Constantine, told to take some time to think over the case, gets sidetracked into fantasizing about his mistress.
    "I, too, have reflected with great earnestness," said the doctor unblushingly, recalling his thoughts from certain pornographic details. "I have thought of many possible theories, but not one that really satisfies me."
• Harsher in Hindsight:
  • Fräulein Schmidt comments on the murder of Daisy Armstrong, saying that a child's murder would be too barbaric an act for her native Germany. The book came out in 1934, and we all know what happened later on.
  • Mrs. Hubbard's constant chatter about her daughter and grandchildren when it's revealed one of her daughters and both of her grandchildren are dead.
• It Was His Sled: Nearly everyone on the train was responsible for the titular murder. This fact has caused quite a problem when adapting the story to the big screen, to which the answer seems to have been fill the train with as many character actors as possible and trust that the audience, many of whom will probably already be aware of the fact that this is the one in which all of the suspects did it, will enjoy watching them act their socks off.
• Moral Event Horizon: The Daisy Armstrong murder; it's why Poirot decides to sweep the conspirators' actions under the rug, because that was just plain karma.
• Nightmare Fuel: The very idea that someone could take your child, kidnap them, hold them for ransom, and kill them even if the ransom was paid.
• Once Original Now Cinnib: This book is THE "Whodunit?" story — it is THE mysterious twist at the end. As a result of Christie flat out making, if not codifying so many tropes in this story, it comes off as unshocking or not surprising at all. The story also just... ends. They solved it, and that's that. One reason a lot of modern adaptations add so many extra plot elements is to make it more intriguing to a modern audience, the same reason modern Sherlock Holmes takes use of original material.
• Questionable Casting: Alfred Molina as Poirot in the 2001 TV adaptation. The beefy six foot Molina feels badly miscast as the short dapper detective, not helped by the choice to dress him like a crumpled traveling salesman.
• Tear Jerker: The murder of the baby Daisy Armstrong and tragic fallout resulting in several more deaths.
• Unintentional Period Piece: Became one immediately upon publication. Several lines are dedicated to the discovery of a large supply of alcohol in Hardman's luggage, and his intention to smuggle what he didn't drink back into America. However, when the book was published in early 1934, Prohibition had been repealed for a couple of months; concealing it was no longer necessary.
• Values Dissonance: Poirot noted, when he was contemplating all of the passengers in the coach and their numerous nationalities, that "only in America" could such a gathering occur. This is used to help him deduce they were all part of the Armstrong household or had connections to the family, and start "casting" them in roles... but not only are some of those role-castings themselves based on outdated views of the nationalities in question, but it becomes rather Harsher in Hindsight considering a) the melting pot view of America has become rather dismissed and fallen out of favor in the years since then and b) thanks to views on immigration changing, it's far less likely such nationalities, or a household containing them, would be as accepted or celebrated today. Even in the time the novel was written, Americans were not nearly as accepting as Christie depicts them (issues with immigrants being a Cyclical Trope, things weren't as bad as in the 19th century, but the stigma was still there), making this another aspect of her Eagleland views. For that matter, many European nations are becoming heterogenous enough that such a mix wouldn't be any less likely there than in the U.S.
• The Woobie: The entire Armstrong family.

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