 During the scene where Corky (Christopher Guest (I) (qv)) is  teaching the cast some dance moves, Eugene Levy (qv) can be seen  in the back behind everyone, almost hidden from view. This is  because whenever Guest would show off his moves, Levy would laugh so  hard that they would have to cut and wait for him to stop laughing  before doing another take. They figured itd be best if Levy was in  the back, where he would not be able to see Guest during this scene.