I hope they reference Glinda's douchebaggery in this movie, when you think about it (as many have no doubt pointed out), in the original movie adaptation SHE is the reason Dorothy is targeted by the WWotW in the first place, and her "you wouldn't have believed me if I told you" justification for not telling Dorothy she could just go home by saying "there's no place like home" was shady even back then.
Plus I hope the 'Ruby Slippers' are the proper 'Silver Shoes' of the original book, as they were only Ruby in the movie to take advantage of the new-then colour in movies...Buuuut if they want to shout out to that particular movie, Ruby Slippers may make more sense.