Have you marked March 13 on your calendar yet? That's when Disney's Cinderella hits theatres, and it's also when you'll get to see Frozen Fever, the short follow-up to the smash hit. This time, Elsa is planning a big party for Anna's birthday, but things don't turn out like she plans. Enter Olaf covered in birthday cake. Take a look at more footage from the film, plus all the wondrous pictures, and watch the trailer below!