I lived in Singapore as a Padbrat from '69 to '73, whilst it was 30 years after the war there were still many reminders, and memories. I remember tales of Japs on bicycles over the Causeway from JB catching the Brits unawares from behind as the Brits were more or less waiting in the coastal bunkers guns pointed seawards away from the invading bicyclists. As we lived in the region at school we tended to look at geography and world history more from the point of view from that region. The clear message that came across was that whilst there was some order to the evacuation/retreat, however if you were unfortunate enough to fall outside the stream of organised chaos you could end up dead, banged up building railways for the next few years, or trying to E&E best you could. Even during the evacuation through some circumstance (the shit happens principle) you could fall out of the stream and end up floundering around Indonesia*.
From listening at school and listening to the older generation talking about events I don't think "fairly chaotic" begins to describe it. One of the wifes uncles barely survived learning how to lay railway lines and build bridges for the Japs. On his return he turned to drink, used to suffer recurring malaria - nowadays he would have been diagnosed with PTSD - lovely bloke when sober. Her dad, the FiL, was in the Navy when Singapore fell at the end of the war and was one of the few non-officer ranks to be allowed ashore. Word had come down from on high that more or less only officers and SNCO's were to be allowed to wander Singapore to prevent any adhoc lynchings, or shootings of stray Japs.
When I was there you could still freely explore Sentosa as it was an overgrown mess. Plenty of the British camps that were on the coast still had the old WW2 pill boxes and gun emplacements in place, all pointing the wrong way. There was even a local militaria dealer who had a warehouse full of old WW2 uniforms, webbing, and paraphenalia from the Brits and Japs.
Note: * You cannot look at images of the region nowadays and consider what happened, and how it happened back then. Singapore is a modern city island, and Malaysia nowadays and it is more or less farming country, office blocks, motorways and high speed rail links from JB up to KL, similar in Indonesia. Even when I was there 30 years after the war Singapore had some wild places, trips up through Malaysia were on roads with dense jungle, or rubber plantations either side. The small islands off Singapore were uninhabited and much of Indonesia was still rain forest. Easy to understand how someone could have become detached, or lost back then.