Kat's swarm of flea-sized mind control robots hop into the ears of the people of Bootsville and soon they all destroy Coop.

Coop uses Kat’s time machine to go back to the past and stop Millie from bringing Kat home, but ends up altering the future for the worse.

Coop tries to undo the Kat invasion, which he brought about by fooling with Kat’s time machine.

Dad accidentally swaps an assortment of Kat's weapons to the unwitting residents of Bootsville.

Kat shrinks Coop and Dennis down to size and tries to squash them like bugs, which makes it hard for Coop to do something big for Dad for Father's Day.