Continuity mistake: The table outside the train, where Hercule and Ms. Debenham were sitting at with the coffeepot and cups, is missing when they stand up and return to the train.
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.
Continuity mistake: In the last scene at the Wailing Wall, Poirot's white pocket square is on the right side of his jacket...where no pocket exists. In the next scene, it's on the correct, left side. Then again, on the ferry, it's back on the right.