Factual error: Poirot gets on the train to London. The engine has an SNCF plaque on it. The video then cuts to the 1936 cycle race. The BCNF was not formed until 1938.
Factual error: The prologue shows the dubbing of a newsreel by a narrator. Ten years later it's 1936. But in 1926 Hollywood was still experimenting with sound film, and a UK news reel would've been silent. (It was 1929 before any sound films were made in Europe).