Plot hole: Dr. King is chasing Hassan through the market. She runs after him at great speed; even assuming that they could have run in a circle for a while, it makes no sense (especially given her role in the plot) that Lady Westholme is one of the people in the market crowd, casually chatting with a merchant, when she was behind Poirot, at the hotel, as the chase started. (01:15:45)
Plot hole: The movie at best is being dishonest with the ending of the chase scene; to keep Dr. King as a possible suspect, the gunshot happens so shortly after she went out of frame (with no cuts) that (since she is -NOT - the killer) there is no possible way that the gun could have ended in her hand. There's also no possible way for the culprit to escape, to find Hassan in the crowd and be there at the perfect moment, etc. (01:16:35)