What are the mistakes or bad points in animl farm by george orwell?

I assume that you are referring to the mistakes that the animals make. This story is very much an allegory of Stalinist Russia or communism as a whole. Old Major had a dream of animal equality. Unfortunately "leaders" like Napoleon took power and became intoxicated with it. Thus began the manipulation and "enslavement" of the other animals. Napoleon simply replaced farmer Jones as a sort of dictator and user of animals. The rest of the farm quickly falls in line through fear and Manipulation. Dissenters like Snowball are chased away.