There are several references to the geopolitical context of the time, which is strongly flagged as 1935-6. There is the main front-page headline in the copy of the Daily Express read by Poirot, which refers to the Abyssinian Crisis. There are prominent portraits of Mussolini. There is Poirot's observation that the harbour on Rhodes is being fortified and finally there is Major Barnes heading to Abyssinia / Ethiopia, on the ludicrous pretence that it's to hunt ostriches.
The plot is based on the 1937 short story "Triangle at Rhodes," from the "Murder in the Mews" short story collection.
First episode to feature a santouri version of the saxophone theme.
Rhodes was once under Italian control. In 1912, Italy seized Rhodes from the Ottoman Empire during the Italo-Turkish War. The island remained under Italian rule until 1943, that is why the police are Italian.