Kimiga miyo oba yachiyo tozo naku'" in the first vocal section is a double meaning of 'chiyo' which means eternity and the sound made by a chidori (plover).
前唄の「君が御代をば八千代とぞ鳴く」というのは、千鳥の鳴き声がチヨチヨと聴こえるので、「千代」にかけたもの。