These accidents occur because, although technically inside the box when she shuffles around the litter, your cat's back end may have been too far outside the box's edge.
Clay clumping litters produce a dust and film when they are cleaned or when your cat shuffles around in the box.
There is no penalty so be liberal with the shuffles, especially if you're stuck.
But otherwise this was a triumph for a batting style which values solidity and balance over soft-shoe shuffles.
The DVD shuffles thru the various scenes on the disc along with some challenge questions automatically so you can host a Seinfeld night or something to pass the time.