Most of the pre-movie Disney or Pixar shorts serve as a nice, tasty appetizer before the main course, but "Get a Horse!" - Mickey Mouse's first theatrical animated short since 1995's nightmare-inducing, childhood-ruining "Runaway Brain" - seems perfect and almost integral for "Frozen." It delightfully sets the stage for what the feature presentation is about to do: take Disney's old traditions and bring them to fresh, blissful new life.