There is a lot that goes on behind the scenes. In this video Rodrigo Prieto, the DOP of the movie, discusses how they used three cameras and infrared markers to make it possible to de-age them in post. He also talks about using different LUTs in different eras of the movie to emulate the most popular film stock colors used in these different times.
What I appreciate is that it wasn't all done with a green screen. The actors actually sat in a car with large LED screens alongside it which showed the roads passing by. This gave the actors a sense of where they were instead of just a green screen, and this projection also lit them in a more natural way than just studio lights would've allowed, and it also reduced budgets as neither the keying was necessary in post production nor the building of a real set that would've been added to the budget.
Doing it this way gives the actors a sense of reality, and they can actually put themselves into a scene, instead of having to imagine it and act the part. I also think that changing the markers on their faces to only be visible in infrared gives the movie a sense of reality, even if they were de-aged.
Is using LED screens playing a video a new method, or is it common in the movie and video world? Let us know in the comments.