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: 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: 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)
Other mistake: Poirot realises that the champagne was poisoned because he happens to notice two cockroaches sipping the spilled champagne instantly died, in fact FIVE are dead when he looks again. This is quite cartoonish; besides the fact that roaches wouldn't die that quickly for that (if they would), we are in the middle of the ballroom/party hall of a luxury cruiser; if the moment something vaguely edible happens to fall on the floor there's half a dozen ravenous cockroaches jumping on it, people have better things to do than dance; that's one massive infestation.
Continuity mistake: When Emily pours champagne for Raymond, David Soul is smoking a cigarette he didn't have a moment earlier. (00:23:00)
Continuity mistake: Dinner on the ship; Miss Quinton takes her nameplate just as a waiter is serving the woman next to Lady Westholme. The man between them is looking in opposite directions in the two shots. (00:14:30)
Other mistake: In Trieste, Carol comments that someone should be with their mother; it seems to be a comment to the fact that she just tripped as it is shown in a wide angle. However, a conversation ensues and Ginevra at the end of it sees through the telescope...her mother trip, again. To make the event even more baffling, Ginny couldn't have witnessed the event from the promenade viewer, the angle is completely wrong. (00:08:45 - 00:09:10)
Other mistake: The spider scene is wildly different when Poirot narrates it at the dinner table (Miss Quinton immediately replies "Oh yes, spiders don't frighten me") compared to the actual scene (she said that replying to a different line). (01:12:20 - 01:33:40)
Plot hole: The movie at best is being dishonest with the ending of the chase scene; to keep Dr. King as a possible suspect, the gunshot happens so shortly after she went out of frame (with no cuts) that (since she is -NOT - the killer) there is no possible way that the gun could have ended in her hand. There's also no possible way for the culprit to escape, to find Hassan in the crowd and be there at the perfect moment, etc. (01:16:35)
Continuity mistake: In the scene at the market in Jerusalem, when Poirot tells Dr. King "Offer him five", the merchant at the stall is standing in front or behind a trinket with a large rectangular pendant, depends on the camera angle. (00:49:45)
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)
Continuity mistake: Poirot is in colonel Carbury's office to convince him not to rule the death as natural. He tells Carbury that he will tell him who the culprit is. Carbury is holding his glass with both hands, but in the next shot as he asks "Well, how long will it take?" the glass is in his right hand since the left hand is busy supporting him against the chair. (00:48:50)
Continuity mistake: Poirot asks Sarah King if the bottle of digitalis in her bag was empty. In the wide angle his index finger is placed on the neck of the bottle, it's much lower in the close-up. (00:47:30)
Revealing mistake: When Dr. King checks on Mrs. Boynton, the dead woman opens her eyes by her own volition before her head rolls back. (00:45:00)
Continuity mistake: Raymond timidly approaches Dr. King at the buffet of the Qumran campsite. A local with a big turban walks behind them right to left to grab something behind the watermelon. Cut to a different angle for a couple seconds, and when we're back to the first, the same extra repeats the exact same movement. (00:38:45)
Continuity mistake: Carol sits down with Dr. King and begins explaining what was her mother did for a living before her marriage. King listens to her with her hands on her knees, which turn into clasped hands at the cut. She then listens leaning her chin against her fist, and under certain camera angles the hand stays there even when she changes position. (00:31:50)
Continuity mistake: Freshly arrived to the hotel in Jerusalem, Dr. King looks down from the balcony and spots Raymond eating something at the table with his family. In the next shot, he's not munching anymore, and he's already smiling at her. (00:28:05)
Character mistake: On the way to Jerusalem, Poirot says that "that man, Weizmann, put it rather well the other day, before Lord Peel's commission", and gives a famous quote about the world being divided in 'two places' for the Jews (those where they are not allowed to live, and those they cannot enter). The movie takes place in May 1937, and Chaim Weizmann's quote is from November of the previous year. 6 months are hardly "the other day."
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.
Continuity mistake: When Emily picks Jefferson's glass, she is holding the bottle of expensive champagne at the bottom of the cloth, and at the top in close-up. (00:22:25)
