Hidden Valley of Oz (c.1951)

Jam, a boy from Ohio, builds a kite and attaches it to a crate and sets off to Oz with his two guinea pigs, Pinny and Gig, and a lab rat named Percy. Once in Oz, Jam realizes his pets can talk. He lands in the Hidden Valley and becomes a prisoner, but they escape and set out on adventures with the Tin Woodman.