[And that, actually, was going to be his next question. What could override the ability of an interdimensional doorway, a path to another dimension? What harbors enough power to supplant them from their universes and pile them into this one, and why?]

Such things exist. [An entity of power, a god-like being, could do so on a whim, and just for the fun of it.] Eager to treat us like playthings to be arranged at will, for no reason other than they're able to.

[He slices a glance towards the store window, though, assessing.]

The nighttime shouldn't have any bearing on whether or not you want to keep looking. I say we venture out for another round, explore where neither of us have been. Your door may be waiting yet.