In the post-credit scene after the credits are over, you see the girls in their lab. Patty has on a headset and is listening to an audio tape, repeating one section several times. Erin asks if she has something. Patty answers, "What's Zuul?"
There's a scene that happens during the first few end credits, that features an appearance by Sigourney Weaver.
As the credits roll you see Kevin dancing and the crowd following his actions. The credits move left to right and change color in reaction to his dancing. Slimer appears at some points and moves.
Slimer moves the first half of the crawling credits from left to right at some points, mainly during Kevin's dancing.
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