This episode's plot is quite slim. The main clues are just a meaningless jumble of train times and destinations, and the dull crime mystery doesn't have much to it anyway. Evidently there wasn't a lot of material to shoot so the proceedings have more padding than David Suchet's Poirot costume. Typical of this is the scene at the morgue. The coroner pulls the sheet back to expose the dressed corpse's head and shoulders for Poirot, Hastings and Japp to look at. After some straightforward dialogue, the camera just lingers on the men standing in silence. After this slowness, Poirot decides to pull the sheet further down. End scene. Inexplicable and silly.
More padding consists of extra wringing of hands and shaking of heads over the murder, plus portentous scenes of Poirot criticizing the criminals for the vicious stabbing alongside pointless flashbacks of the crooks staring at each other through the light of a match.
Which touches upon the episode's worst crime: Despite the lip service about the murder's horridness, the filmmakers exploit it for the crassest scene of violence I've yet seen in the series. Suffice to say it is a drawn-out stabbing where we must watch every moment of the excruciating death, including the scared-eyed victim's cheek smearing down the blood-stained window.
An embarrassment.