Continuity mistake: When Fran first takes the breakfast tray up the stairs, the mug of coffee on the tray is brimming. When she discovers Mr. Thrombey dead, the mug is mostly empty. (00:01:30 - 00:02:11)
Continuity mistake: At the beginning of the movie, Marta is sitting at the kitchen table with her mom while her sister watches crime drama. The arm position of her mom keeps changing during the scene. When she says "Turn it off NOW" she has her elbow on the table leaning on, and then lowers it, still keeping it on the table. In the shots before and after both her arms are off the table. (00:03:00)
Continuity mistake: Marta picks up the phone at the beginning of the movie. In close-up she is holding it with her left hand, but at the cut it switches to her right hand. (00:03:20)
Continuity mistake: Benoit Blanc caught Marta eavesdropping through the stained glass and is doing now "some pokin'." She answers his questions with her arms straight, and listens to him with her arms folded. (00:23:40)
Continuity mistake: Marta recalls in her head the facts of the fateful night during Blanc's coin flip. Harlan sits down in the attic room and grabs the Go pieces from the bag. He places the bag on the table when she tells him to take the "goddamn medicine and go to bed", but it is back in his lap at the cut, and on the table again at the next cut, midsentence. (00:32:50)
Factual error: The damning vials of medication are in close-ups. It is printed on the label that we're talking about 20 ml vials. The morphine vial is 5 mg/ml. When Marta says that she gave Harlan 100 mg of drug she is then wrong; unless she administered the full vial. The two vials have in fact different concentrations: the Ketorolac is in a 30 mg/ml solution, so Marta would have administered 600 mg of ketorolac tromethamine, not 100. The maximum dose for a geriatric patient is 60 mg per day; even the fact that she'd administer it in IV for days for just a pulled shoulder is definitely overdoing it anyway - and she puts even morphine on top of that. (00:36:00 - 01:49:00)
Factual error: The drug in Marta's bag is incorrectly labeled as Ketorlac, when it's Ketorolac, with an extra O. It's the name of the molecule, not a brand name that could have been altered for legal reasons - and they mention the commercial name just minutes later during questioning, with no alteration. (00:36:00 - 01:49:00)
Continuity mistake: When Marta second guesses what she has been doing and holds both vials in her hands, when the camera cuts to Christopher Plummer one vial is still on the table. (00:36:30)
Continuity mistake: Blanc is questioning the security person of the estate. In the close-up you can see him pin a picture to the board using one of the magnets. To the right there's a banana magnet. The tip of the banana on the bottom touches exactly the border of the picture almost in the corner, but in the wider angle we see the photo continues half an inch lower. (00:55:00)
Continuity mistake: Walking outside of the shack with the recording equipment, Marta is rubbing the tape with the magnet. Notice the position of her hand when she is walking - correctly, she is holding the magnet end against the cassette. The close-up that reveals the trick to the audience though, starts with her holding it the opposite way. (There is technically time for her to flip it around in her hand in the couple seconds when her hand is not on camera, but we see her put her hand by her side to conceal the magnet's presence, and then how she holds it tightly against the same spot on the coat; switching the side the magnet is facing would require a deliberate movement with no sense or purpose). (00:57:00)
Other mistake: Marta sinks her white shoes in the mud to cover her tracks. We see that the shoes are, as they should be, all dirty to the sole and welt. They are clean again in the following scene though (on a sidenote, the shoes have been cleaned after the murder then, and she or her mom missed the bloodstain - it's very much possible, it just adds a little implausibility). (00:57:20)
Continuity mistake: After walking in the muddy path, Marta is greeted by very affectionate dogs. Daniel Craig approaches the dogs and the kneeling Ana de Armas with just his left hand in his pocket. Close-up, and he has both hands in his pockets all of a sudden. Return to the first wider angle and Craig's right hand is out of the pocket just as before. (00:58:10)
Continuity mistake: When they are inspecting the outside of the house, one of the dogs brings to Marta the piece of trellis she broke. She holds it in close-up with the loop facing upwards, but as it cuts to Blanc shouting "Sweet beans!" the circle is pointing down. (00:59:00)
Continuity mistake: The lawyer arrives at the mansion and gives the reading of the will at roughly 10:30 am (it's morning, he says he'll be ready "in 10 minutes" and a few minutes after you can see on the phone Jamie Lee Curtis' character holds in hand that it's 10:16). Marta gets immediately stormed by the angry mob of scorned relatives and escapes with Ransom, who drives her to a little roadside inn. It's not implied that they drove hours, but let's just assume it's noon or even past noon (which already seems a lot). Ransom feeds her beans, and Marta is forced by her odd gag reflex to spill the metaphorical ones. When she has just finished telling him how the "suicide" went... it's pitch dark outside, and at the mansion. (01:02:30)
Continuity mistake: Ransom's presence has been incendiary, and everyone is arguing. Walt and Richard get into a slapfest pawing at each other, and Ransom in a close-up says "We gotta do this more often", eating the biscuit. At the cut with Linda shouting "Hey!" and shutting everybody up, Ransom is in the background just contemplating the cookie still in his hand. Similarly, later when Jacob says what he heard and everyone looks at him, he is chewing in the background, but puts his cookie in his mouth in the close-up. (01:02:35)
Continuity mistake: After the reading of the will, the family storms the lawyer. Linda is reading the will holding it in both hands, which becomes one hand at the cut. (01:10:25)
Continuity mistake: When Marta Cabrera and Ransom Drysdale are at the diner the first four times she has three beers in front of her. The fifth cut to her there are four beers in front of her. The sixth cut to her there are three beers again. (01:18:03 - 01:18:27)
Continuity mistake: Marta tries the back door of the apartment and stumbles upon Walt. When they talk, she fiddles nervously with her mail and brings up an unmarked envelope, which should be on top of everything since she just dug for it. When she retreats into the kitchen, she puts the mail pile on the table; in the first shot there's a bunch of business cards on top of everything; after a view of her face and upper body when she is not messing further with the letters, there's a close-up of her going through the mail, and the unmarked envelope is exactly on top, with the cards gone. (01:26:10 - 01:28:15)
Factual error: Opening the blank envelope, Marta finds the fragment of the toxicology report. It is signed "Office of the chief medical examiner, Norfolk County, Massachusetts." But then it writes also the address of said office, which is in Marlborough. Marlborough is also the city when Marta resides, and where the lawyers' letters we see come from. But Marlborough is also a city in the Middlesex county, not Norfolk. (01:28:25)
Continuity mistake: Marta goes to Ransom to tell him about the blackmail letter. During the scene, the position of Chris Evans' hands is inconsistent between shots (he suddenly has his hand under his chin in just a close-up, and he is holding the letter at a different angle when he tells Marta that the toxicity report will shot the overdose). (01:28:50)
Chosen answer: She is holding cake all 3 times, actually, so the only difference is that the first time she speaks. It can be a case of unreliable narrator, but I'd write it down as a mistake (deliberate, probably, as the phrase is important for the plot and they didn't want to hammer it in), since as you said, the other times even when they tell things to the police in a different way from what happened, the details tend to stay consistent, except for parts that are obviously made up, such as who is putting down the birthday cake for Harlan Thrombey therefore appearing subservient and not as close (when Richard tells the story, it's Walt and his wife, when Walt tells the story it is Richard and his wife).
Sammo ★