Night of the Comet (1984)

Synopsis
In this satirical sci-fi comedy, Samantha (Kelli Maroney) and Regina (Catherine Mary Stewart) are two sisters whose father was a hard-bitten Green Beret, but who've grown into typical Valley Girls. They end up spending the night in a steel-lined room just as a comet passes close to the earth, vaporizing the people in its wake. When Samantha and Regina emerge, they discover that they have the city to themselves, and they begin the shopping spree to end all shopping sprees. En route to the mall, they discover Hector (Robert Beltran), the only survivor they've found so far, and they argue over who gets the last boyfriend on Earth. However, the mall holds an unpleasant surprise -- a small army of zombified stockboys who the gals must battle using an arsenal they shoplifted along the way (while lamenting that "Daddy would have gotten us Uzis!" after a MAC-10 fails to fire). Meanwhile, a cadre of soldiers from a special military experiment have come out of hiding, but it seems that they need fresh blood to survive, and Samantha and Regina look like just the refreshment they need. Cult figure Mary Woronov also appears in a supporting role as a scientist. ~ Mark Deming, All Movie Guide