Hange will naturally be very concerned about their little friends and deduce they should not enter the portal because of it.

However they're still going to attempt poking at it. Levi will try spearing a peach on a stick (or his blade, if there's nothing else to use) and stick it into the portal. (If he feels any sort of tugging or the portal attempting to suck him in, he'll dislodge that blade from the trigger handle. Bye!)