Factual error: Before arriving at Brod station the train goes through high mountains. Between Belgrade (Serbia) and Brod (Bosnia and Croatia) it is all flat with no mountains around.
Continuity mistake: At the end when Poirot gets off the Orient Express, he uses the standalone stairs placed close to the rails. As he walks off, the shot changes to the side where he meets a police officer. The shot widens and the stairs are now placed well away from the rails.
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.
Character mistake: In the scene in front of the Western Wall in Jerusalem Poirot says "In the Church of the Holy Sepulchre above us..." but the church isn't located there. It's northwest from there, in the Christian Quarter of the Old City. (00:04:10)
Answer: Not necessarily. Jerusalem is a meeting place of many religions and faiths - and there's nothing to suggest that the Catholic priest isn't there on holiday.
Except it's stated that priest was negotiating market use (with the imam and rabbi). He was a local.
Brian Katcher