Continuity mistake: Race ends up putting the stained handkerchief to (his) left of the gun, but in the close-up of the table the cloth is on the derringer's right. (01:30:30)
Continuity mistake: When madame Otterbourne says hi from her natural element (the bar), David Niven pokes his head in behind Ustinov's, but in the next shot he's not leaning in, he's more like standing behind him, straight. (01:34:00)
Continuity mistake: When Poirot accuses madame Otterbourne repeating the "can't libel the dead" phrase, Angela Lansbury is staring him down with her left hand nowhere in sight. Reverse angle, and she is clutching her pearls with that hand. (01:35:05)
Continuity mistake: Poirot uncovers the dead body in the ice cellar; he does not touch the body anymore, but the hair is scattered on the table in a different position when Race retrieves the pearls. (01:36:45)
Continuity mistake: Inside Pennington's cabin, Poirot finds the document they were looking. He shows it briefly to Race, who is holding a file with a black binding on the right side (so he's holding it the wrong way). George Kennedy shows up in the next shot, and Race is standing there holding the file this time the correct way, and facing the other way after a further cut. (01:38:05)
Continuity mistake: Poirot has a chat with Jackie before dinner after the murder. She says she is ashamed, holding the railing. Poirot tells her that now he, Simon, is available to her again, and Mia Farrow has just the back of her fingers against the railing. (01:40:45)
Continuity mistake: The 'moray eel' on Poirot's plate is shown in close-up. The garnish is on the left side of the plate. In the wide angles though (and at one point Poirot lifts the plate, so we get a good view) the plate is turned differently, the garnish being on the side opposite Poirot's seat. (01:43:00)
Continuity mistake: The pool of blood by the maid's sleeve extends at a different length in the different shots when they find her body. (01:45:10)
Continuity mistake: When Poirot says "That's not quite right" in rebuttal to Race's frustration, he raises his index finger. The same gesture in the reverse angle has him with both index and middle finger raised. (01:46:10)
Continuity mistake: When the doctor arrives at the second murder scene and shouts "Killings, killings!", David Niven by the door is in pose with his arms crossed, and at the cut he has one hand on his knee and the other on the opposite hip. (01:46:40)
Continuity mistake: Salome Otterbourne says she knows who killed Louise Bourget with her own eyes. She waves dramatically her left hand as she says that, and lowers it. Next shot and her hand am raised again, and it's not even the left. (01:49:30)
Continuity mistake: Inside the saloon, Poirot says he knows who killed the three victims. Maggie Smith is looking at him, her left forearm raised. In the reverse shot, her arm is down. (01:52:55)
Continuity mistake: When Poirot calls the doctor's testimony "irrelevant", the doctor's left hand is on his leg, but he's holding his clock's chain in the next shot. (02:00:25)
Continuity mistake: The streak of blood on Simon's neck changes from the first time we see it to the time when the second gunshot is fired. (02:15:25)
Continuity mistake: When Bette Davis' character bids farewell saying that the place resembles a mortuary, Maggie Smith next to her holds her bag to her chest, but in the next shot she is also holding her suitcase with the same hand. (02:16:40)
Continuity mistake: Mr. Ferguson and Rosalie Otterbourne say goodbye to Poirot; Ferguson is holding a suitcase in his right hand, but when Poirot says one last thing to them, the suitcase disappeared mid-stairs. (02:17:15)
Continuity mistake: At the end, when people leave the boat, as seen in the wide shot, the wood plank is at a different distance from the stair's handrail than when Rosalie Otterbourne and Ferguson leave the boat.
