This is a great thread! I just put some parakeet mirrors in my coop. I hung them while they were free-ranging. Well, I went to take a shower while my husband put them back in the coop. From inside the house, I could hear him shouting at the chickens. After about 15 minutes he comes in the house and says he can't get the chickens in the coop. Well, it turns out the chickens saw those mirrors and wouldn't go in! I had to take them down to get them in the coop and then put them back up. Now they ignore them.
I like the idea of the plastic Easter eggs. I don't think they will start playing with their real eggs. They are smarter than that!