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).

This movie reunites comedy partners Dawn French and Jennifer Saunders

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.

The budget on the motion picture is an estimated £120 million.

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.

The boat is named Karnak, after the name of a village in East Egypt, on the Nile.

Despite playing an Armenian, Ali Fazal is Indian.

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.

The guests are seen playing "shuffleboard", a game still found nowadays on cruise ships where players use long sticks with special curved tips to slide disks across a court painted onto the deck.

David Suchet: entering the club during the last scene. Suchet played the title character in Poirot (1989).

The details of Hercule Poirot's military service, tragic love, and the facial scarring that prompted him to grow his iconic mustache were all invented for this film. Despite writing dozens of novels and short stories featuring Poirot, Dame Agatha Christie didn't delve too deeply into his past.

Poirot speaks to Salome Otterbourne of his plan to retire from detective work and grow vegetable marrows. This is what Poirot does in The Murder of Roger Ackroyd.

In Murder on the Orient Express (2017), Poirot says he likes symmetry (same sized eggs, stepping in poop with both shoes, etc). He says to Ratchett that he doesn't like his face, likely because of the asymmetrical scars. In this film, the audience finds that Poirot's own face is also asymmetrical and he grew the large mustache to hide it adding a new depth to the previous film's conversation.

Much like Murder on the Orient Express (2017), the main murderer of the movie attempts suicide to prevent being taken by the authorities. However, in Death on the Nile (2022), the suicide attempt is successful while in 'Murder on the Orient Express', the main murderer attempts to kill herself, but Poirot has removed the bullets secretly in order to get her reaction and confession.

Jacqueline's .22 caliber pistol is a heavily engraved Sharps four barrel pepperbox of mid 1850s vintage. It features a rotating firing pin rather than the rotating barrels of most other pepperbox pistols.

Some major changes from the book plot: 1. Many characters have been deleted, combined, or have different relationships to each other in order to simplify the casting. Some examples: Bouc plays the role of Poirot's assistant, as well as jewel thief (Colonel Race and Tim Allerton, respectively). Bouc's mother is an entirely new character (Ms. Allerton). Dr. Bessner is now Lord/Dr. Windlesham, a former fiancé of Linnet Ridgeway Doyle. Marie Van Schuyler and Nurder Bowers are implied to be romantically involved with each other. Andrew Pennington has been changed to Cousin Andrew Katchadourian. 2. Louise Bourget is murdered outdoors on the ship's staircase. Her body is thrown overboard only to get caught up in the steamer's paddle-wheel. The blackmail money is found in her pockets instead of torn in the clutches of her hand. 3. Salome Ottourborne does not get shot as a result of witnessing Jacqueline De Bellefort escaping the scene of Louise's murder. Instead it is Bouc who witnesses the actual murder itself. 4. Bouc is killed while being interviewed by Poirot with Simon Doyle as Witness, in a darkened saloon. Simon does not shout warnings to Jacqueline, but rather cues an already waiting Jacqueline when to shoot Bouc. 5. Bouc and Rosalie Ottourborne witness the shooting in the saloon 6. Rosalie is now the niece and manager of Salome. Salome's occupation has been changed from an author to a singer 7. Jacqueline and Simon die as a result of one gunshot. During a final embrace, Jacqueline points the gun at Simon's back and shoots through him and into herself. They die in an artistic pose, propped against a chair. 8. There is a Mexican standoff during Poirot's revealing of the murderers. 9. Instead of nail varnish being used to fake the blood stains on the handkerchief, it is red paint. In fact, Simon gets upset at Louise for forgetting Linnet's blood red nail varnish at the hotel, and has to substitute that with the paint. He uses the same handkerchief to tend to his real gunshot wound and has evidence of his own blood on it, before throwing it into the Nile with the gun and Ms. Van Schuyler's scarf. This is what conclusively tells Poirot that Simon was involved in the murder. 10. There is no "J" written in blood above the wall in Linnet's room. 11. The stone that almost falls on Linnet and Simon is pushed by Andrew at the temple of Abu Simbel

When the bodies are carried off the Karnak they are not covered in shrouds, but wrapped completely, like mummies.

While the plot of the film is consistent with that of the novel there are several changes which are made, mostly to condense aspects of the novel and to add extra resonance for the characters. Several characters from the novel are condensed into one in order to cut down on the number of characters in the film. In addition, in the novel most of the characters, aside from cousin Andrew and Louise, have no connection to Linette, they simply happen to be traveling on the same ship. In order to provide more emotional resonance, and more potential suspects, the film gives every character a connection to Linette and her family. Bouc does not appear in the book, and thus does not die. In the book it is Salome Otterbourne who witnesses the maid's murder and is, in turn, herself killed. Since Bouc does not appear in the book, it is Poirot's friend Colonel Race who acts as sidekick to the great detective. The film also invents all of the prologue to Hercule Poirot's time in Egypt, including the scene where he encounters Simon and Jackie in London, and the flashback to his time in WWI.