The Murder of Roger Ackroyd - S7-E1
Factual error: A few drops of acid are dropped on a penny and the liquid bubbles (colorless liquid) as the acid eats its way through the penny. The penny is mostly copper. Any acid that can react with a copper will also produce a bright green to bright blue solution of dissolved copper, which is not the color seen. (00:05:20)
Suggested correction: Not necessarily. It depends on the acid and its strength. A weak acid may only oxidise copper to a monovalent state (Copper (I)) (which is colourless) rather than its divalent (Copper (II)) state which produces the blue solution.
Dumb Witness - S6-E4
Factual error: Spoiler. Police Sergeant Keeley tells Poirot that Doctor Grainger died of carbon monoxide poisoning. The killer turned the natural gas in the bedroom and did not light the heater. This would result in the room filling with natural gas, not carbon monoxide. (01:17:30)
Suggested correction: Surely it was coal gas at that time, before we all converted to natural gas?
The product of coal gas is still methane, which is CH4. It may contain tiny volumes of CO but the gas asphyxiation would still have come from methane, not carbon monoxide.
Factual error: Poirot smells and very carefully tastes a drink and says, "Potassium cyanide." It is impossible to distinguish between potassium cyanide and sodium cyanide (the other common cyanide) by this method. In addition, there are another less common cyanides that would smell and taste the same as potassium cyanide. (00:16:01)
The Million Dollar Bond Robbery - S3-E3
Factual error: The stock footage of the Queen Mary coming back from the US and docking in Southampton is not in black and white, and it certainly is more recent. The crowd wears colorful clothes, no hats, neon lights are used for the building illumination, and the cars parked are of modern design. It's a post-WW2 world, not 1936. (00:38:40)
The Million Dollar Bond Robbery - S3-E3
Factual error: As the title of the episode says, it's a million dollar robbery, in bonds. Problem is, as seen when the bag is loaded, the million is in 50 dollar bonds, which was the lowest single denomination for Liberty Bonds. 20,000 big bond notes would never fit in that bag, and would weigh a lot! Funny mistake, considering that the reality of 'weight' of a sum is a problem in many movies dealing with regular dollar bills, but bonds would have much fewer limitations as for the denomination of a single note (could have been a pile of bonds worth $10,000 or $5,000). (00:19:50)
How Does Your Garden Grow? - S3-E2
Other mistake: After Katrina is arrested, Mr. Delafointaine is reading about it on the newspaper. The newspaper is dated Thursday 23rd May 1935. The date is correct, the whole investigation does happen in a day, starting around 10 AM; Poirot is greeted by the couple with "Good afternoon" and to imagine that by the time he gets to their home Katrina's news (complete with picture of the arrest!) is already in a late edition of the newspaper (a local one, at that) is a bit too much of a stretch, with all the steps taken for the investigation, everything in broad daylight. (00:43:20)
How Does Your Garden Grow? - S3-E2
Factual error: Poirot and Miss Lemon go to the riding school to meet the solicitor of the deceased. Parked in the road right as the camera pans, and featured for a few seconds, is a car Morris Eight series II, a 1938 model while the episode (as made abundantly clear by the fair invite and banner) is set in 1935. (00:28:25)
How Does Your Garden Grow? - S3-E2
Continuity mistake: Poirot asks Dr. Sims "So the Delafontaines, they were dependant" etc., the doctor's right hand changes position between shots, and the hand positions keep alternating between the two versions depending on the camera angle (an item suddenly appears in his hand when Miss Lemon mentions the living relatives, too). (00:26:30)
The Mysterious Affair at Styles - S3-E1
Plot hole: To enter Mrs. Inglethorp's bedroom, Hastings and John have to ram the door and certainly break the lock (it is replaced, so there was damage done). The doctor leaves the house very early in the morning just after ascertaining the death of the woman, and tells them he "locked both rooms" (the room has three doors but one is bolted internally, allegedly). But the door was broken, and in fact when Poirot arrives, which is early in the morning, as Hastings went to the village waking him up, he finds a brand new lock in the door. They would have needed to summon a locksmith at maybe 6 or 7 am, to repair an internal door in a country house, and he should have done it on the spot (also, the door frame itself is more likely to suffer damage than the lock itself, no real damage was shown during the scene). The keys are also all in the same bunch and not looking in any way different (one should be brand new and shiny). (00:28:45 - 00:37:40)
The Mysterious Affair at Styles - S3-E1
Continuity mistake: Poirot is concentrating in London, making a house of cards. When he says "I steady my nerves, that is all", the 6 of hearts can be seen in his right hand, and he sets it as the diagonal piece. Cut to Hastings, and then Poirot supposedly still has the same house in front of him...but it is not. Where the 6 of hearts was, there is now a 6 of spades, and the whole castle is different, with the cards pulled tighter together. Later he rebuilds the house, and he sets horizontally in the close-up a 5 of spades, which turns into the 2 of spades immediately after. (01:19:40)
The Mysterious Affair at Styles - S3-E1
Factual error: Poirot is taking a break from the prosecution' speech and is walking with Hastings, explaining to him Mary Cavendish's jealousy. In the street, they pass by a truck (registration plate MR 5496) that is a Morris-Commercial 1-Ton model. Morris began productions in the early 20s, and we are in 1917 for this episode. (01:17:45)
The Mysterious Affair at Styles - S3-E1
Continuity mistake: The guests of Styles Court manage to get inside the room of Mrs. Inglethorp and talk to her before the second fatal crisis happens. In the first wide shot you can see Hastings peek at Lawrence and then look towards the fireplace, which is an action he'll do in the close-up that follows - Lawrence does not seem to look in the direction Hastings is checking out, at all, but that is actually a nice touch considering the resolution. Moreover, in the second close-up of Hastings looking at him (the one that follows the view of the fireplace), Mary is directly in front of Hastings, you can see her insignia and arm. But instantly she is shown at the cut, creeping along the wall behind Lawrence. (00:29:00)
The Mysterious Affair at Styles - S3-E1
Factual error: At the local food store, Poirot is talking with the shopkeeper. In the background are plenty of food packages that show the great care for authenticity that is a mark of the series. I feel like disputing at least a couple; the Polly box with a parrot is a Taormina American-made can that should be a product of the 20s, and the Brown and Polson's Patent Corn Flour has a claim on the box that says "65 years world-wide reputation." The patent is a 1856 one and the annexed name is from 1859 (previous ads with established date show that year as the one they started counting from); in 1917 the box would have not said "65 years", it hadn't even reached 60. (00:19:20)
The Mysterious Affair at Styles - S3-E1
Continuity mistake: At dinner, Alfred Inglethorp asks Hastings what he's going to do after the war. The person to his left is placing a glass on the table. The next cut happens mid-sentence and in that instantaneous timeframe the glass is perfectly still while the wine was still noticeably moving in the previous shot. (00:10:10)
The Mysterious Affair at Styles - S3-E1
Factual error: The movie opens with Hastings watching a news film about the "New Flanders Offensive." It says that on "7th June 1917 General Haig attacks Ypres", but at the beginning of the year Sir Douglas Haig was promoted to Field Marshall. A news propaganda reel would surely have called him with the appropriate title. (00:00:35)
The Mysterious Affair at Styles - S3-E1
Continuity mistake: The coroner asks Mary to tell everyone about the quarrel. Frontal shot of Mr. Wells; he is pointing his hand with the spectacles at a certain height. Reverse shot; the hand is lower, resting on the other hand, and only then he raises it to the same level as it was in the other shot. (00:53:40)
The Mysterious Affair at Styles - S3-E1
Continuity mistake: When Evie Howard leaves the house after the argument with Mrs. Inglethorp, she sits on the sofa explaining what happened to Hastings and the others. She has her hands on top of the purse handles. After a brief cut on Mary saying "oh no", one of the handles is free. (00:16:40)
Factual error: The basis of the blackmail is based on the Japanese invasion of Manchuria because howitzers were supplied to bombard Shanghai. Shanghai is not in Manchuria. (00:35:41)
Continuity mistake: When Miss Lemon announces Mr. Halliday, Poirot has two open letters on his desk, side by side when the camera is positioned behind the desk, which turn into one (probably one on top of the other) when the camera is positioned in front. (00:07:00)
The Million Dollar Bond Robbery - S3-E3
Continuity mistake: In the cabin of Mr. Ridgeway, Poirot approaches the portmanteau. In the close-up the tie covers completely the lock before Poirot pushes it aside with his cane, but in the wider shot part of it was already visible, uncovered. (00:24:25)
