Fridge / Teenage Caveman

• Because it's The '50s, the subtle hint this is not the past is easily missed, thanks to the casting habits of that era. However, the very Caucasian, very modern looking humans who are supposed to be cavemen are not, instead being modern humans After the End. Not only is it Fair for Its Day, but it's downright progressive.
• Fridge Horror: The narrator says he saw many civilizations rise and fall - and he notes that the recycle of violence has continued long enough for dinosaurs to re-evolve over the course of millions of years.
• Those cavemen probably didn't eat very much because they make A LOT of noise with those rattles when they hunt, which would scare off any animal they're trying to catch.