What features of the second and the third parts of Things Fall Apart contradict the first part?
I'm not quite sure what this question means, but many of the contradictions have to do with the character of Okonkwo and the arrival of the British. In these chapters, what were seen as "strengths" on Okonkwo's part (his masculinity, courage, prosperity, etc.) have now become weaknesses. He is broken by his years in exile, and the destructiveness of his anger is more evident than ever. His farm and crops are gone, and although he has 2 beautiful daughters ready to marry, he cannot initiate his sons into titled society immediately, as he intended. As he recognizes the threat the missionaries pose to the village, he speaks out, encouraging the men to go to war. Yet no one listens, and his frustration showcases how his bravery has become a liability.
In addition, solid foundations of the Ibo culture are cracking and splitting. Social structures are shattered by the acceptance of outcasts into the Christian church, and the converts grow bolder in their attacks on their native religion/society. This pits brother against brother, slowly eroding centuries of culture and civil structure.