- All-Star Cast: The film stars Albert Finney, Lauren Bacall, Sean Connery, Ingrid Bergman, Michael York, Vanessa Redgrave, Jacqueline Bisset, Anthony Perkins, Martin Balsam, Richard Widmark, Jean-Pierre Cassel, Sir John Gielgud, and Dame Wendy Hiller, among others. Bonus point since they are not only international stars, but also all famous in their respective countries.
- Awesome, Dear Boy: Deliberately invoked. Sidney Lumet thought the best way to assemble an All-Star Cast was to hire the biggest star first; at the time, that was Sean Connery. It worked; Richard Widmark signed on to play the victim for no other reason than to meet the other stars.
- Cast the Runner-Up: Ingrid Bergman was originally offered the role of Princess Dragomiroff, though Sidney Lumet told her she could play any role of her choosing. After reading the script, Bergman bypassed Dragomiroff in favor of Greta Ohlsson, the Swedish nurse. Lumet advised against it, reminding her that the nurse had fewer scenes than the Princess. But Bergman felt an affinity for the role, and her instincts paid off when she won an Oscar for it.
- Creator-Preferred Adaptation: 84-year-old Agatha Christie attended the movie premiere in November 1974. It was the only film adaptation in her lifetime, that she was completely satisfied with. In particular, she felt that Albert Finney's performance came closest to her idea of Poirot (though was reportedly unimpressed with her sleuth's moustache). The premiere would be her final public appearance: she died fourteen months later, on January 12, 1976.
- Deleted Scene: The photo gallery on the German DVD by Kinowelt includes one photo hinting at a scene not used in the final cut. It shows Bianchi in his bed on the train with Pierre standing beside him.
- Fake Nationality: The Belgian Poirot, the Russian Princess Dragomiroff, the Hungarian Count & Countess Andrenyi, the German Hildegarde Schmidt, the Greek Dr. Constantine, and the Italian-American Foscarelli are all played by British actors; and the Italian Bianchi is played by an American.
- On the other side, Swedish Greta Ohlsson and French Pierre-Paul Michel are played by a Swede and a Frenchman respectively (a rare time Ingrid Bergman could play a character of her nationality,) and most of the American and British characters are played by American and British actors.
- Playing Against Type: Sidney Lumet was best known for directing serious, gritty crime dramas set in New York. This isn't one of those.
- Production Posse: Lumet previously directed Sean Connery in The Hill, The Anderson Tapes, The Offence; and they'd work together again in Family Business.
- Underage Casting: The 37-year old Albert Finney as the 55-60 year old Hercule Poirot.
- What Could Have Been:
Trivia / Murder on the Orient Express (1974)