I assume this is a multiverse situation, and at the end of the party they go back into their normal timelines, only with the experience of that gathering now with them.
No changing the past for yourself, but maybe changing the course of all of theirs based on how they react. With that in mind, I can’t think of a single thing I’d say that would help any of them, except maybe:
“Let’s all work on figuring out how this happened, because this rather breaks the universe, doesn’t it?”
Bro, you explained the situation better than I ever could. I didn’t even think of the premise of the multiverse but it makes much more sense