hey man just remember once the salt is all gone there is often a little bit of liquid water on top of a layer of ice. that can be some slippery ****
i dont remember the movie, but if thats what happened it can still make it uber slippery
edit: i guess i just took this for some kindergarten knowledge since im from a cold state. people, during the winter you throw down salt on your driveway, the state salts/sands the roads. this is done to lower the freezing point and therefore melt snow/ice and prevent ice from forming on surfaces.