Para a segunda pergunta: Jay Oliva não é estranho para o universo DC e um artista de storyboard para B v S, diz Estas são memórias futuras causadas por um "Time Boom" da viagem de Barry através do tempo.
"You want to know the answer? Okay... you've watched The Flashpoint Paradox, my movie, right? In the DC Universe in the comics, there's this thing where-- it's a little different than the Back to The Future thing where you can go back in time and change your threads and stuff, but in DC, when you go back in time you create this kind of 'Time Boom' kind of thing where lots of things change.
"Okay, so let me just tell you this. Again... I don't know if this is Zack's thinking, but this is mine: what if that isn't a dream sequence? What if what you saw was a Time Boom, a latent memory from the future when Flash comes back? If you look at the cut, he doesn't go to sleep! He's waiting for the [Lexcorp file decryption] and suddenly this [Knightmare sequence] comes in, and he's jogged out of it seeing his own death. And what does he see? He sees Flash. And if you're a DC fan, you know what's happening. You know that Flash going back in time, that memory is now coming back to him... mind you, it's jumbled." - screenrant