Franz, the protagonist of the story "The Last Lesson" by Alphonse Daudet, noticed several unusual things on the day of his last French lesson. These unusual things are discussed below:

1. Silence in the Classroom: On the day of the last lesson, Franz noticed that there was an unusual silence in the classroom. The students were not talking or making noise as they usually did. Everyone seemed to be lost in their own thoughts.

2. M. Hamel's Attire: Franz noticed that M. Hamel, his French teacher, was wearing his best clothes. He had put on his beautiful green coat, black silk embroidered waistcoat, and frilled shirt. His hair was combed and he had on his finest shoes. This was unusual because M. Hamel usually wore his old brown jacket.

3. Decorations in the Classroom: The classroom was decorated with flags of different countries. There were pictures of French cities and maps of France on the walls. This was unusual because the classroom was usually plain and boring.

4. Importance of Learning French: On the day of the last lesson, Franz realized the importance of learning French. He noticed that everyone in the class was paying close attention to M. Hamel's lesson. They all wanted to learn as much as they could before it was too late.

5. Emotions of the Students: Franz noticed that the students were emotional and sad. They knew that this was their last French lesson with M. Hamel and they would never be able to learn French again. They had taken the language for granted and now they regretted not paying more attention in class.

In conclusion, Franz noticed several unusual things on the day of his last French lesson. These things made him realize the importance of learning and appreciating the things we have before it's too late.