Factual error: Attention to detail in props is always extremely high in this series, and tubular flashlights have been in circulation since the beginning of the century. However the one that the supposed burglar is holding as they make their way through the top floor of the villa looks perfectly modern and unlike any model compatible with the 30s. (00:10:20)
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)
Continuity mistake: When Gertie and Joey make their escape running down the stairs of the hall, they pass by a couple (she has a white hat and a blue dress). When Poirot and Japp run after them, the same couple has jumped back several meters. (00:43:00)
Double Sin - S2-E6
Continuity mistake: In the car chase, when the woman turns to check the police behind them, the close-up on the steering wheel does not match the position of her hands before and after. Similarly her passenger has the right hand visible when it shouldn't be. (00:28:45)
The Disappearance of Mr. Davenheim - S2-E5
Continuity mistake: When Poirot does the newspaper trick for Miss Lemon, the final reveal has him present the newspaper holding it between index and thumb in the front view, index and middle with the thumb sticking out in the back view. (00:42:10)
The Adventure of the Western Star - S2-E9
Revealing mistake: Japp is waiting for Van Braks to make his move, and when he is hopping on a taxi for the airport, he begins to tail him. When the car moves, reflected in the door is a modern No Parking cone in bright yellow (incidentally, they also pass by a parked car with a FUU 692 plate that is a bit too recent for the series, being an Austin Big 7, first produced in 1937). (00:41:05)
Double Sin - S2-E6
Continuity mistake: When Hastings storms out of the antique store claiming to have solved the case, Poirot follows him until he turns into an alley. In the view from the back of the alley, there's a man with a hat who walks all the way past Poirot and turns the corner into the main road. In the reverse angle, the guy is still walking down the alley in front of Poirot. (00:42:30)
The Disappearance of Mr. Davenheim - S2-E5
Other mistake: When Japp and the bobby arrest the pickpocketer, the dialogue says "It was only last week that we put him inside for three months" which obviously does not make sense. In the original story he did the 3 months of jail the year before, and this has to be a flub in the lines of this TV version (it is specified also that he did those in the winter, so the Sergeant can't possibly mean that he was released last week). (00:35:00)
Continuity mistake: The cream colored shoes of the Lady are prominently featured in the finale. When the actress has to run, not only are the heels replaced by modern tennis shoes, but they're black, in contrast with her white stockings. (00:46:40)
The Disappearance of Mr. Davenheim - S2-E5
Continuity mistake: Carving the distant relative of his parrot for dinner, Poirot slices one side in the close-up, which turns out to be the exact opposite side in the wider shot. (00:38:35)
The Disappearance of Mr. Davenheim - S2-E5
Continuity mistake: The race is presented through actual footage of the era, with a cameraman from Pathe shown, saying that Lowen's car is number 3. But the car shown in the stock footage is different from the one Lowen is driving, which does not even have the number in the same position. (00:33:10 - 00:33:45)
The Disappearance of Mr. Davenheim - S2-E5
Continuity mistake: When Poirot at dinner asks the first question (the bathroom one), he does not have his large napkin in his vest. When he asks the second one (the bedroom one), the napkin he had for all the rest of the scene is back. (00:40:15)
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)
Factual error: Poirot is cycling through Wimbledon; he passes by a house which has a definitely non-1930 car in the yard, and a yellow alarm box on the first floor. (00:18:20)
Continuity mistake: Poirot rudely awakens Hastings with his three questions. You get a good view of Hastings' wristwatch on the bedstand. When at the end of the Q&A Hastings turns his attention to the watch, it is in a completely different position. (00:41:25 - 00:42:35)
Revealing mistake: The stuntman smashing through the window is quite obvious - he does not even have the hair styled like Hastings'. (00:31:30)
The Adventure of Johnnie Waverly - S1-E3
Continuity mistake: When Hastings stops his car in front of the train station at the end of the episode, he talks to Poirot holding his hand on the outer circle of the steering wheel, or on the inner part in the reaction shots. (00:49:20)
The Adventure of the Clapham Cook - S1-E1
Continuity mistake: When the mysterious Aussie lawyer gives Miss Dunn his card, he hands it to her with the fingertips pinching the paper in the top corner, while in the reverse shot he's holding it by the bottom corner. Also, just a moment later she gives it back to him using her right hand. Unfortunately, the card was in her left hand. (00:30:20)
The Adventure of the Clapham Cook - S1-E1
Continuity mistake: Hastings is reading a letter that makes him go "Good Heavens." He is holding the letter by the top left corner, which becomes the top right in the (lack of) reaction shot from his Belgian friend. (00:24:20)
Visible crew/equipment: At the very end of the episode, as Poirot's car drives off headed to the harbor, filming equipment is neatly reflected in the door. (00:51:40)
Answer: He definitely says "Belgian", but the subtitles get it wrong and show him saying "American."
Wblank71