I'm a well read technosexual who's bluntly honest about all things, although I try to be most honest about myself.
So this promises to answer the questions about The Comedian's button and how that ties into Rebirth. The problem? I haven't read Rebirth. (Which, yes, there was Batman: Rebirth, Rebirth was what this whole retcon was named, and there was an issue simply called Rebirth.) So I do feel slightly out of the loop and I'm kinda itching to get Rebirth to see what's what, and how The Watchmen, and that whole alternate universe DC world, ties into this event, and what's happened to these characters and those apparently missing ten years. I haven't quite picked it up yet, though.
When Reverse Flash hits up the Batcave, Batman has to hold the villain off until Flash gets there. (He'd been trying to figure out the button mystery and had called Flash over; in the middle of a fight already, Flash promises to get there in one minute.)
Except... something happen. Reverse Flash claims to see God, although given that he's gone into the Watchmen-verse, people are guessing he saw Doctor Manhattan. This continues in The Flash, which I don't read regularly. I don't reward companies who do these kind of crossovers, because they're hoping to get me to buy another title, and penalizing me if I don't invest in another title. Seeing as I read Batman for the author, I have no interest in picking up Flash as a pull, so I refused to buy Flash 21. We'll see how the next Batman goes...