Thanks for the feedback!
The bug you noticed is already on our list for stuff to fix, shouldn't be an issue in next week's update anymore ;D
BUT you can actually restart a level by pressing 'R', this would've helped you when the box-out.of.bounds-bug happened.
Just look at the Controls-Page accessible through the game's main menu or the game's description, all controls are explained there.
But you are right, we should have added another help-message telling the player about the restart-feature in game