Starring: David Suchet, Hugh Fraser, Philip Jackson, Pauline Moran
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)
Plot hole: The hole in the hat was pre-existing and the bullet was fired in advance and dropped. Poirot notices immediately the hole when Nick puts the hat down but somehow missed it while she was wearing it as she supported him. He also does not notice that the bullet has not been fired at that time - which would have been still hot if just fired, not at all if dropped. Most importantly, in the spot where they were sitting, it's not even possible to think where a shooter could have ever been hidden; nobody wonders where the mysterious shooter could have been or cares to investigate the circumstance despite knowing the very moment the supposed shot happened. The fact is basically ignored throughout the rest of the episode.
The Tragedy at Marsdon Manor - S3-E6
Samuel Naughton: Was the accomodation all right?
Hercule Poirot: No, monsieur Naughton. The accomodation was all wrong.
Samuel Naughton: Oh...
Hercule Poirot: The duck-feather pillows. It feels as if the duck are still in them. (00:14:50)
Trivia: Poirot in the ship's lounge is reading the actual May 1st 1935 issue of Bystander (recognizable by the cover and with the correct page order, does not seem to be a simple movie prop), roughly consistent with the time frame of the first season and a contest taking place on the 14th. (00:07:50)
The Murder of Roger Ackroyd - S7-E1
Question: The doctor (James) put on a Dictaphone to make the suggestion that Roger Ackroyd was alive at 21:30 hrs. But how could he know that someone (Paton) would pass the door of Ackroyd's study at precisely that moment?