[She's a teenager, of course she's sure! It has nothing to do with her knowing the future. Really. Don'tthinktoomuchaboutthat.]
We're underwater in some alternate dimension and we don't know if it has an Aquaman. How are we gonna get out of here? Can you contact someone?
[Because her communicator sure wasn't working, but there's always the hope his was. If he was taken from the day the Flash Museum opened, then that means it's after the League expanded, right? There should be more people. Someone has to notice Wally's missing the day of his museum opening. Batman was supposed to be watching him so the Rogues didn't kill him that day.]