Factual errors: The paper boy at the newsstand announces "Gershwin dies!" Poirot opens the newspaper, which features the obituary of famed American composer George Gershwin. On the opposite page is the obituary of Laura Welman, and the date on the newspaper states that it is September 1937. George Gershwin died on July 11, 1937.
Anachronisms: When Poirot gets into a taxi he asks to be taken to 'The British Library.' This was not created until 1973. He should have asked for 'The British Museum' or 'The British Museum Library.'