Continuity mistake: In the scene where Bette Davis has lost her shawl there is a shot of her and Maggie Smith from far away. They talk about the time and in the background Angela Lansbury is drinking. She puts down her glass and leans her head on her hand. Then the shot changes to a close-up of Bette Davis and Maggie Smith and you can see Angela Lansbury in the background, with the glass in her hand, just about to take a drink. (00:55:05)
Continuity mistake: Take a look at the Karnak temple scene when the massive stone block is pushed off the column to kill Linnet. Seconds before the stone falls, the column and parts of the floor beneath are brightly lit by the sun. Also notice that the stone is positioned maybe 2 yards off to the right of the column's centre. When the stone is coming down in the next shot, most of the column (and the ground) is suddenly in the shade. And when the stone hits the ground it is no longer positioned to the right of the column but in front of it. (00:47:40)
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.
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: 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: 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: 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: 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: When Mrs. Van Schuyler mentions a "popping sound", David Niven's position is different in the two takes; first his hands touch, then he suddenly has one hand on the armrest. Similarly, when she mentions "an indifferent champagne" her hand is on her embroidery, but she was gesticulating away from it before the cut. It's then Peter Ustinov's turn to be inconsistent; Niven asks "Could it have been a small pistol" etc. and Ustinov is fingering his moustache, but in the next shot he isn't. (01:29:00)
Continuity mistake: Race hears Poirot's morse code and grabs his mighty swordstick; look at his tie. When he's inside Poirot's room, his Royal Green Jackets tie is styled different; in his own room the small end reach approximately the second-to-last red diagonal stripe of the wide part, while in Poirot's room the small end reaches barely the third-to-last stripe. (01:26:40 - 01:27:15)
Continuity mistake: Poirot watches Jackie leave the hotel seemingly falling for Simon's ruse. He's having breakfast; when he puts the croissant in his coffee, the hand holds the brioche with its flat side upwards. Ustinov in close-up is eating the brioche with the curved side up. (00:27:00)
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 Colonel Race comes to Poirot's rescue, Poirot's arm is outstretched and stays that way even after a reaction close-up on Peter Ustinov with his arm lowered, as you can tell by the part of his arm in frame. (01:26:55)
Continuity mistake: When Race and Poirot lift Simon Doyle from the bed, he helps himself up using Peter Ustinov's arm in the first shot, David Niven's in the second. (01:20:05)
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: 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: 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: 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: Poirot enters his bathroom to freshen up. There's a brush on the left side of the sink, placed on top of a box. When the cobra sticks its head up, the brush rests directly on the sink. (01:25:40 - 01:26:05)
Continuity mistake: When Jane Birkin is talking to Poirot in French, David Niven is leaning against the back of her chair with his hand. Cut, and he's watching her with his arms crossed. (01:22:05)
