It probably contains codeine or somekind of other opiate.
No, NyQuil contains dextromethorphin hydrobromide monohydrate. Along with the alcohol content this makes it very hard to stay awake after drinking.
Some people have taken large amounts of cough syrup with this active ingredient in order to hallucinate. I've heard it called "Robo-Fry" from people trying it by drinking Robotussin DM.