Character mistake: Poirot identifies Prof. Hardman's revolver as a 1927 police-issue weapon due to its blued finish and chequered grips. In fact, these features were common in the widely-available civilian versions of the Colt 'Police Positive' revolver and not the least bit specific to police-issue weapons.
Continuity mistake: While on his way to the Wailing Wall, Poirot gets camel dung on both of his shoes. When he arrives at the Wall mere moments later, however, his shoes are completely clean.
Revealing mistake: As the train approaches and stands in Brod Station, it becomes rather obvious that the smoke emitted by the steam locomotive is "painted in" by computer. It does not move or change shape as real smoke would. A shame, as the steam effects earlier in the film are very realistic.
Factual error: When the steam engine is derailed and is surrounded by snow from the avalanche, there would be a high risk of the boiler and/or firebox overheating. Under these circumstances, the driver would "drop the fire" by opening the bottom of the firebox to drop the coals onto the track. This would cause delay in restarting the train, so the passengers would be taken to safety and warmth by a rescue train.
Answer: Dickens used satire, irony, and humor as a means to express social criticism and political commentary. His novels were filled with comical characters and colorful dialogue. He used a humorous writing style to expose the Industrial Revolution's harsh and negative impacts like poor education, worker exploitation, social inequality, and other societal ills such as extreme poverty, domestic violence, alcoholism, and so on. Poirot is obviously responding to that.
raywest ★