There are very few things that cannot be remade in Fallout 4 or Grand Theft Auto 5. With the power of mods and sheer willpower, anything can be done – anything. Recreating the Justice League trailer from San Diego Comic-Con in Fallout 4 probably didn't even make YouTuber UpIsNotJump break a sweat – especially not after recreating Captain America: Civil War's trailer in GTA V.
The real question here is why Chris Evans is the Batman. I mean you have to admit, the guy that is supposed to be Ben Affleck (Batfleck) looks quite a bit like Captain America. The Flash is just completely on point though.
Overall, this is a pretty damn good recreation!