Warning: Movie spoilers throughout this post.
The movies starts with a crumbling feudal system. The toys belong to their owner and they are characterized as their property. It is underlined that they have to be loyal to their owner and that a life without him is wrong. The system falls apart since the owner shows no longer interest towards the lives of the toys. The toys, having lost their faith in their owner, decide to escape pursuing a better life.
Toys emigrate to Sunnyside, where a communist system is advertised. There is no owner of the toys and they are many kids who can play with them. The community seems welcoming and appears to solve all their problems. It turns out that the advertised system is a dictatorship with Lotso being the one who is in absolute authority. Furthermore, the toys are divided in two classes where the upper class takes advantage of the other one. The oppression is unbearable and they decide once more to escape.
Meanwhile, Woody has come in contact with the benevolent dictatorship of Bonnie who cares about her toys. Nonetheless, he decides to escape in order to help his friends. Back to the Sunnyside, Lotso and his company have tried to allure Barbie to join their ranks promising the realization of her dreams in exchange of their friendship with the other toys, outlining another dominant theme of the movie, the relationship among the toys. A theme which is enforced by learning the background of Lotso and his alienation in order to avoid getting hurt emotionally.
During the revolt, we learn that the system that Lotsa has imposed has forced the way of living of some toys in the upper class, which have to guard the new toys in order to enforce discipline.
At the end, we observe that the change is unavoidable. Andy hands over his authority to Bonnie, giving the freedom to the toys to live more adventures, instead of staying idle for the rest of their lives. At the kindergarten, we see an utopia where all the toys live in harmony.