Mistake 1: treating nominative and ḍamma as synonyms. One is a grammatical case; the other is its sign here.
Mistake 2: classifying دَلْو and ظَبْي as having only estimated case just because they end in wāw or yāʾ. The book treats them as sound-final equivalents.
Mistake 3: excluding رِجَالٌ merely because it is plural. It is a fully declinable broken plural and takes these same signs.
Mistake 4: calling وَدَلْوٌ an independent subject in the author's list. It is a coordinated noun sharing the first noun's case.