The mad hatter is at the trial cause he is the first witness to be called to trial. he is called to the trial by the rabbit that has a horn. The horn he has is used to get the attention of the crowd also to call up witness. As the trial goes on Alice continues to grow At the same time she begins to forget things. the reason for this is cause she is starting to wake up. Also i think that her dream is being influenced from noises from the world she lives in.