Many of the characters are combinations or alterations of characters from the novel, to make for a smaller cast and a less confusing plot. Salome and Rosalie Otterbourne, a romance novelist and her daughter, become a singer and her niece/manager. Andrew Pennington becomes cousin Andrew Katchadourian. Marie Van Schuyler, a socialite and no relation to Linnet, becomes Linnet's godmother who has the ideals of Mr Ferguson, the aristocrat turned socialist. Windlesham, a character mentioned in the first chapter, is combined with Dr Bessner to become Dr/Lord Windlesham. Bouc, a character who appears only in Murder on the Orient Express, takes on elements of Col. Race while his choice of traveling companion, his mother Euphemia, is reminiscent of the relationship between Tim and Mrs Allerton.
This movie has been delayed several times. Originally set for a 2019 release, a delay in filming pushed it to 2020. Then, due to the COVID 19 pandemic, it got pushed around several times, until being set for fall 2021. Then on April 3, 2021, it was pushed back to February, 2022, by the Armie Hammer accusations.
Tiffany & Co designed jewelry worn in the film, most prominently Linnet's diamond necklace. The necklace features a replica of the Tiffany Yellow Diamond, one of the largest yellow diamonds ever discovered. First discovered in South Africa in 1877, as of 2022, it has only been worn publicly by four women. At the 1957 Tiffany Ball, it was worn by Mrs. E. Sheldon Whitehouse. It was worn by Audrey Hepburn for Breakfast at Tiffany's (1961) publicity photos. Lady Gaga wore the diamond at the The Oscars (2019). Beyoncé wore the necklace in a campaign with Tiffany in 2021.
In both this film and Murder on the Orient Express (2017), Poirot shows signs of being obsessive compulsive (Letitia Wright's character even calls him "obsessive" at one point). His need for balance and symmetry is shown when he sends back one of the desserts so that he has an even number and when he straightens the feet of one of the victims. Obsessive-Compulsive Disorder (or OCD) is considered a relatively new discovery, but the term was actually coined in 1877 by German psychiatrist Carl Westphal.
Salome Otterbourne is clearly based on real-life Sister Rosetta Tharpe (who just might have invented rock and roll). Five songs in the film are performed by Tharpe, and a sixth Tharpe song is performed by others.
Sir Kenneth Branagh has known Jennifer Saunders (Marie Von Schuyler) and Dawn French (Bouwers) since the mid 1980s when he met them through his then girlfriend and future (now ex) wife, actress and writer Emma Thompson. In the UK, French and Saunders (1987) have been a famous comedy double act since the 1980s, having known each other since university.
This version of Poirot is implied to have been born much later than his literary counterpart, who was in his fifties at the beginning of the Twentieth Century. In this movie, Poirot is shown in the prologue as a young soldier in 1914, making him at least thirty years younger than Book Poirot.
The film's "S.S. Karnak" was built in the studio parking lot. It is based on the P.S. Sudan. Dame Agatha Christie wrote "Death On The Nile" based on a trip on the Sudan. Built in 1921, she was one of the largest river steamers in Thomas Cook's Nile fleet. The steamer spent the latter years of the 20th century laid up and in deteriorating condition until new French owners bought her in 2000 and returned her to service in 2001.
While sitting and admiring the Sphinx, Poirot can be seen sitting by a table on which are two eggs in cups. This is likely a reference to Sir Kenneth Branagh's earlier Poirot film, Murder on the Orient Express (2017), in which Poirot is struggling to find two eggs of the exact same size for breakfast.
A large number of the shots are framed with perfect or near-perfect symmetry. Some scenes are shot from more than one angle yet the symmetry remains. This is, no doubt, an allusion to Poirot's obsessive need for balance in all things.
The majority of the film's lead actors (those featured above the title on its posters) can be said to be "trading accents." Americans Annette Bening and Armie Hammer speak with British accents. Many of its main British & Irish actors use either an American accent (including Sophie Okonedo, Letitia Wright, and Jennifer Saunders) or a French/Belgian one (Rose Leslie and, of course, Branagh's own Poirot). Indian actor Ali Fazal speaks with a British accent. Gal Gadot is the film's only non-British main actor to speak in her offscreen accent (Israeli), as she does in nearly all of her films.
Shot entirely on large format 65mm film. Sir Kenneth Branagh's previous turn as Hercule Poirot in Murder on the Orient Express (2017) was also shot in this format as well as his adaptation of Hamlet (1996).
At the beginning of the film, Poirot is asked by a reporter if he is, "on the Aurendel Case". This is likely a reference to the Poirot novel, Dumb Witness, the plot of which surrounds a family surnamed, Aurendel. This may be the novel the third installment will be based upon.
At the end of Murder on the Orient Express (2017), Poirot is told of a "death on the Nile". In the novel "Death on the Nile", Poirot was on the boat before and at the time the first murder was committed. This might or might not constitute a discrepancy, as the "death on the Nile" mentioned at the end of Murder on the Orient Express might refer to a death that occurs prior to the first death in the novel. In the beginning when the primary characters are introduced, it is revealed through exposition that the case Poirot was summoned to investigate was an entirely different crime.
Stacy Abalogun is listed in the cast as "Elinor Glyn". Elinor Glyn (1864-1943) was a British novelist specializing in controversial (for that time) romantic fiction. (One bit of contemporary doggerel, inspired by her work, asked, "Would you like to sin/With Elinor Glyn/On a tiger skin?/Or would you prefer/To err with her/On some other fur?"). For the source novel, Dame Agatha Christie created Salome Otterbourne as an alcoholic romance novelist, loosely based on Elinor Glyn.
Gal Gadot's character Linnet Ridgeway was said to have played Cleopatra in a play in her school days, and there is a scene where she dresses as the historical figure. In 2021, Gal Gadot announced plans to produce and star in a film based on Cleopatra's life.
The leather blinders Poirot wears while sleeping are shaped like his signature double-layered mustache.
In 2022, the Tiffany necklace would be worth nearly $41 million based on inflation alone. However, its status as an original Tiffany would make it worth significantly more, possibly over $100 million.
Jodie Comer was initially listed as one of the cast members. However, despite that announcement, she didn't officially sign on to the film due to scheduling conflicts.
Poirot is depicted as serving in the Belgian army in WW1. This goes against the literary canon, where Poirot is established as a refugee who moves to England (Mysterious Affair At Styles). Even assuming Poirot was invalided out of active duty to an allied country, that wouldn't make him a refugee.
The cast includes one Oscar winner: Sir Kenneth Branagh, and two nominees: Annette Bening and Sophie Okonedo. This is in stark contrast to the 1978 version which included five Oscar winners and two nominees.