Read the comic here.
No, I don't know where the Fireman found the hat, eyes, or broom. Just work with me here; I've got 48 random items to incorporate into a storyline.
I suppose it should count for something that the Fireman doesn't refer to their "evil plan". Just...."our plan."
Actually, spamming the world about a box of LEGO fire seems a bit more like "evil", no?