The Adventure of the Cheap Flat - S2-E7
Factual error: When Poirot asks O'Brian about unsolved crimes with young couples as suspects, he says "There's that Bonnie and Clyde of course, but they're at large somewhere in the American Midwest", to which Poirot replies "And let us hope that is where they remain." Bonnie and Clyde were killed in Louisiana on May 23, 1934. The episode is set in October 1935. (00:12:20)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Poirot knocks at the door of The Black Cat, next to a street worker and a pimp. Nobody is walking down the street in the wider shot, but in the close-up an elderly couple passes by. (00:22:55)
The Adventure of the Cheap Flat - S2-E7
Other mistake: Spying on the Italian embassy from Japp's van, the building has 2 Italian flags of the period. But the rightmost one is mounted upside down, with the crown under the shield instead of the opposite. (00:23:05)
The Adventure of the Cheap Flat - S2-E7
Factual error: Agent Burt brushes off Poirot's question saying "When will you guys understand there is no such thing as the Mafia, the Black Hand or the Cosa Nostra?" The last term he uses, while not impossible (since members of the organization were indeed referring to it as such) is a huge improbability, considering that officially FBI (and certainly the general public Burt is lashing at) came to know the real name (adapted in "La cosa nostra") only decades later with the Valachi investigations. (00:24:05)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Poirot is doing his round of phone calls at night clubs looking for the chanteuse; the pen before Hastings' arrival is pointed to the left side of the screen, when he sits down (and Poirot has not touched it) it points to the right. (00:24:40)
The Adventure of the Cheap Flat - S2-E7
Character mistake: Bernie Cole "King of the clubs" greets Miss Lemon and tells her she'll find Elsa "Straight down the corridor, second on the left." So she opens the second door...on the right. And it's the correct one. (00:30:50)
The Adventure of the Cheap Flat - S2-E7
Continuity mistake: Miss Lemon, as Penelope Maitland, enters the performer's room. The shady character that opens the door does it holding a cigarette in his left hand. The hand is kept close to his chest in one shot, while it's on the door in the reverse. (00:31:35)
The Adventure of the Cheap Flat - S2-E7
Plot hole: The professional hitman from the US does not have a gun of his own, and does not bother in the long time elapsed between the apartment's hit and the nightclub (it could even be hours) to check if the gun he just grabbed is loaded or not. Who in the world would not take a split second of his time to peek at the cylinder and see how many bullets does he have? An assassin planning to kill with that gun, even.
The Kidnapped Prime Minister - S2-E8
Continuity mistake: When Poirot tells his tailor that it's his equipment that is at fault, Hastings holds the newspaper in ways not coherent between shots (he folds it, but in the reverse shot is still looking at the top of the page, and so on). (00:04:20)
The Kidnapped Prime Minister - S2-E8
Factual error: The Austin used by Poirot and his company to go to the attempted murder scene and back is an Austin 18, which entered production in 1937, later than the event of this season/episode. (00:12:00)
The Kidnapped Prime Minister - S2-E8
Continuity mistake: Poirot opens the car window in two shots; in the first he is holding his walking stick close to the body, but in the second he has a completely different posture, with the cane perfectly vertical and his arm at a right angle. (00:13:20)
The Kidnapped Prime Minister - S2-E8
Continuity mistake: At Scotland Yard, Poirot is readying the glasses for the moment when Japp will pass him the paper he's reading, about the driver. When the view switches, his hands, that were above the desk level, start off from underneath the desk. (00:33:35)
The Kidnapped Prime Minister - S2-E8
Factual error: The calendar behind Japp in Scotland Yard places November 13 as a Tuesday, but that is wrong for 1935, when the story is set (the whole season consistently goes with 1935 historical facts, Poirot in this episode makes a reference to "the Dutch", and the newspaper page Hastings shows up with at the end of the episode talks about the notorious gangster's death, happened that year). It was a Wednesday in 1935, to be Tuesday it should have been 1934. (00:34:00)
The Kidnapped Prime Minister - S2-E8
Factual error: When the former Mrs. Daniels hops on her car followed by Hastings, between them you can see a speed bump, not a feature on roads in Britain (or anywhere) at the time. (00:36:55)
The Kidnapped Prime Minister - S2-E8
Continuity mistake: Hastings has lost sight of the car he was pursuing, and stops at the crossroads. In the wide shot you can see his left hand holding the top of the windshield, but in the close-up he's using just his right hand. (00:40:40)
The Kidnapped Prime Minister - S2-E8
Factual error: At the end of the episode, during the fitting of the jacket with monsieur Fingler (last role of character actor Milo Sperber), Hastings is reading a newspaper prop sporting a doctored first page (the real headline, which was about Italy, is replaced by the fake PM speech) of The Daily Express based on the real Friday October 25th, 1935, which is wrong in month and day of the week (the appointment was on Thursday and it's supposed to be November going by the various calendars seen throughout the episode). (00:51:00)
The Kidnapped Prime Minister - S2-E8
Factual error: Poirot in this episode has to save the Prime Minister, kidnapped before he could attend the League of Nations Disarmament Conference. This episode is set in November (the previous of the season in October), but it can't possibly be 1935, since the Disarmament conference happened between 1932 and 1934. It makes mention of the PM being vital to have at least a chance at preventing Germany's rearmament, with Hitler withdrawing Germany from conference and League of Nations entirely in October 1933. It should be noted though that the conference happened in Geneva and not in Paris like it's described here. The original material did not have this sort of inconsistency since it was set to happen much earlier in the century and for the Treaty of Versailles, where Paris would have been the correct destination. Both short story and adaptation have as prime minister a fictional "David MacAdam", with him designed to be a stand-in for David Lloyd George, just recently replaced as PM.
The Adventure of the Western Star - S2-E9
Continuity mistake: In his preparations for the arrival of his idol, Poirot sets a bunch of flowers with a card ("Mlle. Marie Marvelle"). When we see the bunch later as Poirot has to leave to go to her, the card is absent - but he has not touched the table. (00:03:55 - 00:05:15)
The Adventure of the Western Star - S2-E9
Character mistake: While handing Mademoiselle Marvelle's letters to Hastings, Poirot calls him "Chief Inspector". (00:06:55)
The Adventure of the Western Star - S2-E9
Continuity mistake: Mademoiselle Marvelle outstretches her arm to hand Poirot the menacing message; her hand does not move in the following shot, but when we get back to a full view of Rosalind Bennett, she is holding the card with her arm bent. (00:07:05)