We use allusions everyday, an allusion is a reference to a person, place, thing, or idea wich characterize for having ceirtain cultural significance. That means, they are known by some or great part of the society. In this way, the audience can relate to the idea and figure out the meaning of the message received.
In this case, the family is making reference to famous movie, "The Wizard of Oz". Dorothy (the main character) finally finds out how to get back home, she only needs to say and think "there's no place like home" and click her heels together three times. So the family, after a long journey finally gets the chance to return home back to normality.