Did you say "not discovering talking hills"?
Were they meant to have, but didn't? Or did you get that wrong? Or why did Waldorf say they were alive if they wern't? Sarcasm maybe?
The Pigs in Space discovered no life on Koozbane, so they went back to their ship. After they left, two hills start talking. A wife hill thought they heard some noises. But the husband hill tells his wife to go back to sleep.
And Waldorf shouts. "The hills are alive!"
Also, I didn't realise that Statler had children! If so he must be married too. But, who to? Waldorf's sister maybe?