Sans lets the portal close after them - he mostly did that for funzies, because he just as easily could have teleported them, albeit with some uncertainty as the layout of the room inside. As they get in they're see shelves of binders filled with notes, and some computers have that been left running, along with various machines and storage devices. Storage is a strange thing int he Pokemon world.

There's not actual point to this quest when it comes down to it. It's not like they are going to do anything with this information, besides be fascinated by it. Probably.

"Did you talk to anyone about the spacial rifts that happen here?" he asks conversationally.