I saw a production in Pittsburgh with the original script a few years ago. It mostly lays there like a dead fish, and then one HILARIOUS scene which was probably not intended for comedy in the original draft was wisely played as a joke instead.
When the boys have returned to the present, they go to a nightclub, and keep having musical flashbacks to the events in Brigadoon. It plays like a Mel Brooks scene if you do it "wrong," and if the rest of the show had been that whimsical, it would have been a much more enjoyable experience, despite the wonderful voices of the cast.