Urusei Yatsura 2: Beautiful Dreamer (1984)

Lum is a cheerful alien who now lives with her human fiancée, Ataru and her goods friends on earth. The night before the school festival, the world begins to change, things seem to be repeating themselves. Gradually, all necessary functions come to a stop, people disappearing, streets deserting, buildings decaying except Lum and her friends who live ever happier. When they begin to probe the truth, they find out it's somebody's dream that is changing the world...