De acordo com o diretor do filme, as crianças não apenas sobreviveram, mas prosperaram. De alguma forma, apesar do fato de que isso está bem abaixo do população viável mínima , eles foram capazes de repovoar a Terra.
Q. That's what's so scary! And it takes so long for the train to blow up! There is ... nobody left!
Bong Joon-Ho: I don't think Nam is an anarchist though. He just wanted to blow up one train car. It's the avalanche that kills everyone else. It's the revenge of nature, if you will. Also, avalanches are most prevalent in March or April, when the snow is slightly softer, just like in Nam's dialogue. That's when avalanches happen, usually. Yes, they're all dead, and that's a bit harsh. But it's a sci-fi film: If you can't say these things, or have these ideas in a sci-fi film, where can you?
The idea of there being multiple generations of people on this train is a key one. There's an expression in the film: "train baby." Those are the two kids that survive, the ones that only knew life on the train. Someone like Curtis or Nam, they lived on Earth, then boarded the train. These kids have never known what it was like to step on the earth. So it's almost like Neil Armstrong touching down on the Moon when they leave the train for the first time. They have no memory of what it's like to be on the Earth. For them to procreate, it's going to take a little time. So, for me, it's a very hopeful ending. But of course there are so many deaths, and so many sacrifices ... it's not so sweet. But those two kids will spread the human race.
Nenhuma explicação é dada como eles conseguiram, exceto que não é tão fria quanto antes imaginado .