Factual error: Right after the movie shows us a sign telling us that we are in NJ in 1937, here you have Ginevra Boynton reading the March 1938 issue of Daring Detective, which even plays a larger role in the story later. (00:00:35)
Factual error: The Italian flags used in the city that stands in as Trieste are all modern flags of the Italian republic, with just the tricolour. In 1936 the flag would also have the coat of arms from Savoy, being still a kingdom. (00:08:30)
Factual error: Poirot meets the rest of the cast at the port of Trieste before they sail off for Jaffa. In actuality though, they already were in Jaffa, which served double duty acting as a very poor stand-in for Trieste; the architecture of the port and promenade is nothing like Trieste's, and you can see in the establishing shot Jaffa's St. Peter's church. (00:08:30)
Factual error: Carrie Fisher and David Soul kiss in 1936 Trieste in front of a poster for the stock cube "Arrigo" from local food company Arrigoni. Sounds fine, but the ad used was launched in 1939. (00:11:30)
Factual error: After Lady Westholme commented on Poirot's absence, and we saw him seasick in his cabin, the focus is again on the Boyntons. In the background you can see the ship's other guests entertaining themselves with a dance. They are dancing to the tunes of a rearranged version of "Ta-Ra-Ra Boom-De-Ay", which is perfect for the time period, but their dance is a version of the "Lambeth Walk." The movie takes place in May 1937, and the musical "Me and my girl" that invented and popularized this dance would debut in December of the same year. (00:15:10)
Factual error: The car Poirot and Dr. King use to get to the hotel escorted by colonel Carbury (and then to Qumran) is a military Humber Snipe Mk II, making its first appearance in 1938. The movie is set in May 1937. (00:27:00)
Factual error: The movie is set in May 1937, considering that the finale happens during the coronation ball for George VI, May 12 1937. However, in an earlier scene in the hotel lobby (when the matriarch blocks her son's path with her cane) Poirot is reading a copy of The Palestine Post from July 8th of the same year. (00:34:00)
Factual error: Thanks to Poirot's aggressive bargain, Dr. King pays the butterfly pin 5 dinars. We're in 1937 Jerusalem, but she's using to pay a modern (contemporary to the day of the shooting) 5 Jordan dinars bill, in a country that at the time had the Palestine pound as currency anyway. (00:50:00)
Factual error: When Poirot sets his trap about the "brown spider", the man next to Lady Westholme is intently reading an issue of Pic magazine; it's the July 1938 issue with Carol Landis on the cover. But the movie is set in May 1937. (01:12:30)
Factual error: Emily on the ship orders a bottle of Louis Roederer's top of the line champagne, Cristal, with its distinctive bottle, and specifically the 1929 vintage. In 1937, it'd have been a bit too much "top of the line", though; Cristal was commercial produced only since 1945, so in 1937 when the movie takes place you wouldn't have been able to casually order it for dinner on a cruise ship.
Factual error: The movie presents the location of Qumran as a tourist destination with intensive excavations. In 1937, Qumran was definitely not a tourist spot; it was not unknown, but the name value of the area was established only after the discovery of the Dead Sea Scrolls a decade later.
