15:43 - Annihilation is a term used to describe the absolute destruction or cancelling out of something, used often in science to describe particles cancelling each other. In the case of ZS, material fairies and material evils do the same thing.

16:46 - The text on the side of this news helicopter reads "Every Other Day Newspaper," a pun on the major "Everyday Newspaper" in Japan.

21:07 - To elaborate on the note in the episode, a zashiki-warashi is a "good luck child." In Japanese folklore, the appearance of the happy little kid is usually accompanied by a general improvement in the luck of the household. See the linked webpage for more details.