Isn’t that the halloween episode where Quimby insults the entirety of France and France launches a neutron bomb on Springfield, which flies through the city before exploding? It passes Quimby’s office, he looks out of the windows and is annoyed the he will surely be made responsible for this (don’t know the exact english wording what Quimby said, because I saw that episode only in my native language localization).

I like to imagine that the building is on a truck surrounded by other buildings on trucks moving a couple miles down the road, but the gag there is Homer jumping over to the Moe’s truck

I can guess this episode in one try, no more, no less.