Salome's guitar cable disappears from when she enters the room playing, walks through the dance floor and ends up on the stage.
When Poirot is interrogating Euphemia, Bouc, Rosie, and Salome; the orientation of Rosie and Salome's hands changes from one shot to another. The way Salome has her right hand on her hips keeps changing, and the way Rosie has her fingers on the banister also keeps changing from cut to cut.
Poirot grows a mustache to hide the scar tissue that covers most of his upper lip and cheek. Scar tissue cannot grow hair at all, as it does not contain follicles or sweat glands; it is a connective tissue that grows between the dermis after it is split. Poirot's mustache could therefore never be as full as depicted, and should have several holes or irregularities.
A ship in Egypt at the time would have had an all male crew. Also the crew (both male and female) are shown wearing shorts and short sleeve shirts which completely transgress dress norms for the era in Egyptian culture. Men would have either worn western type suits or shirts and trousers or local dress which again would have covered arms and legs.
Poirot's facial wounds would be heavily dressed or already sutured but certainly not let wide open.
The doctor states that the character died at least six hours ago, but when he touches her hands, the wrists do not show any sign of rigor (rigidity), which is first observed two to six hours following death.
The lighting on the ship, particularly the deck lighting at night is far too bright and too white in tone to be realistic for a ship built/operated in the 1930s. The lighting would be a much warmer tone and lower level given the bulbs at the time and the modest electrical output of a ship's generator.
The Belgian army is shown using gas on October 31, 1914. Although the first known use of poison gas in WW1 was by the Germans in April 1915, tear gas was used by the Allies starting in August 1914. And although the type of gas being used isn't mentioned, it is unlikely that poison gas is what is being deployed in this scene, given that many of the attacking Belgian soldiers aren't wearing gas masks.
At the end of Murder on the Orient Express (2017), Hercule Poirot is told of a murder on the Nile and is called to investigate it. In Death on the Nile (2022), the murder does not take place until 1 hour and 5 minutes into the movie. However the movie itself in the opening scene in the night club has a character greet Poirot with "You solved the case in Egypt". This is a different one.
Bouc greets Poirot ("Of all the pyramids in all the world...") in 1937 Egypt in a way that seemingly references the 1942 film Casablanca ("Of all the gin joints in all the towns in all the world..."). However, Bouc's greeting only has one repetition, unlike the anaphora in Casablanca which echoes twice. Bouc's greeting is an ordinary witticism for period people, even though, to modern ears, it might break immersion.
When Poirot is interviewing Bowers, in 1937, she mentions the loss of her fortune ten years ago when banks failed. Market crash was not until 1929, not 1927. While factually correct, 10 years ago instead of 8 is an acceptable and common colloquialism.
Throughout the body of the film, the skin around Poirot's mustache shows no sign of his wartime facial scar, yet the scarring is there at the end when he has no mustache .
While this film has its share of anachronisms and other lapses, two revealing errors come in rapid succession. First, a cloud of "balloons" is released from the riverboat--but they sail off upwind, in the opposite direction from the smoke trailing from the smokestack. Second, a few minutes later, the passengers are carried from the Abu Simbel tomb on sailboats, but the main sheets (ropes holding the booms) are all slack despite the wind seeming to fill out the sails.
Bouc's jacket flies the opposite direction of his kite.
The doctor states that one of the victim's throat was cut. The audience can see a scar but not an open wound.
There is no need for a backstory to Poirot's iconic mustache. Many men at the time would grow mustache, side-burns, beards, all sorts of well trimmed and complicated facial hair styles.
The film is set in 1937, but Salome Otterbourne is shown numerous times playing a semi-acoustic guitar. Guitars spotted in the film include a 1952 Gibson L5 and a reissued Gibson ES-250. The ES-250 was first made in 1939. Guitar models too late to have been used in 1937.
When Poirot goes to watch Salome in London, the guitarist is using a tremolo effect. Although tremolo has been used in music for centuries, the first tremolo electric guitar pedal was not commercially available until the early 1940s, at least 3 years after the time period in this film.
The Mausoleum of the Aga Khan is shown in the background near Aswan, however construction on it didn't even start for 20 years after the time period of the film (completed 1960).
Everything about the ship (rooms, interiors, exteriors) seems so pristine & new, yet the center interior stairway on the up/down steps facing each other have numerous worn paint spots on the handrails and steps. How could it this way on such a beautiful vessel.
Poirot's lips are not moving when he says "I asked you not to come" to his girlfriend in the military hospital.
When Bouc speaks to Rosalie in front of the Temple of Abu Simbel, Bouc says "Yes" while his mouth does not.
The establishing CGI portrayal of the Pyramids at Giza is highly inaccurate. They do not align symmetrically with the Sphinx as shown, nor are they on the bank of the Nile, but are about 8 km west of the river.
Linnet surely would have had the time and possibility to rent the whole boat for the whole trip so that other passengers could not embark later on.
The hooded character being pursued by Poirot could just turn around and kill him in cold blood instead of trying to flee.
The doctor does not react to hearing a gun being shot; his instinct or medical professionalism should have triggered him to go and look for wounded patients.
Poirot has his index finger on the trigger of a cocked gun. As a former soldier, he should know that this is too risky and could lead to an accidental shot.