In the 1982 classic, E.T., when Elliot and Mike take E.T. out on Halloween, E.T. sees people dressed up in bizzarre costumes, but when a kid dressed up like Yoda walks aside, E.T is seen rushing towards him saying "Home Home". Now Yoda is a fictional character for people on earth. How come E.T. recognizes him and relates to him. Did Steven Speilberg want to suggest by this scene that may be Yoda actually exists? What's the meaning behind this scene?
Its just a gag/joke or just a promise between Spielberg and Lucas (who knew each other from film school) started from E.T. and ended on Star Wars Episode I: The Phantom Menace.
So its a promise between Spielberg and Lucas that both allow to use each others character in their films like gag.
Their is a good link to read on this Does Earth Exist In The Star Wars Universe?
Even a similar question present on Scfi as Are E.T. and Star Wars in the same universe? with a good analytic answer.