Real-world shots of crowds running scared in the streets do not match the shots of Nancy walking down the empty model streets. Some of the model buildings are noticeably different, too.
The sign outside the drive-in theatre advertises the films Yentl and The Adventures Of Milo And Otis. However, when Daryl Hannah's character looks over the top of the screen, the original 1958 version of Attack Of The 50 Foot Woman is playing.
When Nancy lifts the roof off Honey Parker's nail salon, Honey and Harry are standing still. The next shot is of Harry diving under a sink some distance away.
When Nancy first begins to grow, all of her clothing bursts off except her bra, which grows with her body.
During a closeup of Nancy's face when she opens her eyes after collapsing on the farm building, a fleck of lipstick is visible on one of her teeth.