The Wrong Side of the Tracks/From Hero to Eternity/And the Kitchen Sink - S1-E1
Other mistake: From Hero to Eternity: When Petunia and Toothy are making the snowman and Toothy tries to put the hat on its head, in the beginning of the shot, there is a random smaller hat on the snowman's top button, which disappears mid-shot. (00:09:55)