A scene that comes to my mind is when Methuselah, the parrot left by Brother Fowles, squawks out the word "damn". You laugh at this until the three older daughters are punished by their father. Since he can't pin the sin on any one of them, he punishes them all. The girls don't let their father know that it was their mother who taught the word to the parrot.
This relates to a theme of the novel dealing with free will. Nathan Price controls the lives of his family and doles out punishment upon them for the smallest thing. He's cruel in his treatment of them just as he's cruel in his treatment of the villagers.
Methuselah also serves as a symbol of how vulnerable the Republic of Congo is just after its independence. Methuselah is unable to protect himself when he's let loose, and he is killed by a predator. The predator is a symbol of the U.S. who "kills" the newly-found independence of the Congo.