There were doubts about Jedi regarding the creation of the clone army, there were even hints that the Jedi council had started the investigation. In the movie, the members of the Jedi council all shown their concerns about Palpatine. At the time of the attack of clones, there were about 200,000 clone troopers, than pretty soon the number reached 1.3 million during the Battle of Geonosis. This was due to the fact that at Kaminoan, the planet where clone troopers were created, the facilities which were scattered across the planet could product millions of clones. So it sounded like, it started as a pet project with a lot of potential to grow.

Originally, the movie Revenge of Sith would tell more about Sifo-Dyas, the Jedi master who ordered the creation of clones, but it was dropped perhaps to shorten the movie. More about him appeared in the separate novel.