That looks like one of the fruit platters that you can find at any grocery store, so it probably came like that. I noticed them too, and after a little research, I found out grapes are okay for rabbits in small amounts. I'm sure a few dozen grapes split between thirteen rabbits won't cause any harm.
(I don't know I actually love snakes, and the bush viper is one of my favorite snakes. I think snakes are cute, but I know that's not the common opinion.)