Disappearing shapes?

Great interactive app. But why do the shapes disappear? It seems like theres a bug that allows the little one to push the shapes through a "hole" in the border of the screen. Not sure how else to describe it, but I noticed that the shapes go through the hole and never come back, but the app keeps going...the backgrounds continue to change every 30 seconds but theres nothing to do as there are no shapes to rattle! Is this on purpose?

Other than that, great app. My 10 month old has been enjoying it since she was 4 months, and now shes figured out how to manipulate the shapes!

ARRQUEENS about Smart Tot Rattle - Cause And Effect Sensory Stimulation