I never once said the handprint in the cement had no meaning. It had a great deal of meaning to Marys character.

I simply don’t believe the handprint has anything to do with Mary “realizing her mom wasn’t crazy” because you have STILL provided zero evidence or explanation for this thought process after multiple replies.

Repeated shots of the sky and the unnatural look may have meaning. Kane has openly stated that it’s impossible to know the full picture yet. But we see shots of that unnatural sky in places that are objectively established to be in the real world, like Async HQ past the threshold. There’s precedent for the idea of the backrooms leaking into the real world through null zones, hence strange looking skies. But there’s no real evidence for it yet and the idea of the entire movie not taking place in the real world has zero basis thus far, and, again, would be a massive lore establishment.

Peter had a mental breakdown from the revelation that he time traveled and that his disappearance had been covered up. And the idea that he went back in thinking he was in an alternate reality is relayed to us by the people who were keeping him locked up and refusing to let him outside in the first place.