I made it up the tall tree on the left of the level that seems impossible at first and jumped off the top of the level but was sad to not find any Easter egg up there.
It looks and sounds really great but it isn't possible to steer the ball by hitting with a particular side if the bat. This takes a lot away from the gameplay. It would be awesome to see an update with some sort of contact-point rebound angle implemented.
I thought I'd found the secret...