End of a nursery rhyme, or the fate of this puzzle's other three long answers

Question:

Answer:

ALLFALLDOWN

Length:

Similar Crossword Questions:

Feature of six other long answers in this puzzle
Feature of this puzzle's three long Down answers
Simple substances split in eight long answers in this puzzle
Game in which the puzzle's long answers are pieces
Cryptographers' successes (and what can be found in the circles in this puzzle's long answers)
Chemical reaction phenomenon, and what occurs in four symmetrical pairs of long answers in this puzzle
Like the identified car models inside this puzzle's long answers
Thought hidden in eight long puzzle answers
Magic words ... or a hint to the other long answers in this puzzle
"Two-way" thoroughfares at both ends of this puzzle's long answers
Nursery rhyme line that finishes this puzzle's theme
Each of this puzzle's long Across answers sounds like one
Speak derisively, and a hint to how this puzzle's long answers were created
Show since 12/17/1989 whose five main family members are hidden in this puzzle's other long across answers
It uses only the 12 letters A, E, H, I, K, L, M, N, O, P, U and W (like eight long answers in this puzzle)
Brief version of this puzzle's title hidden in eight long puzzle answers
State short forms strung together in 12 long answers in this puzzle
List shortener hidden in eight long puzzle answers
Provide recon, and another hint to this puzzle's long answers
Phrase whose abbreviation is the key to four long puzzle answers
Main thoroughfare in Manhattan (one can be found in each of the four long answers in this puzzle)
Puzzle title people hidden in eight long answers
What each of the four long answers in this puzzle is
Rhyme runaway, and how this puzzle's theme answers are formed?
Reservoir, and hint to puzzle theme found in seven long answers