Elio Petri's "La classe operaia va in paradiso" shows a very subtle cameo of Ennio Morricone, who also composed the original score of this film, awarded with a Palme d'or in the 1972 Cannes Film Festival. The Italian Maestro appears in close-up for almost one minute as the anonymous--and obviously uncredited--blue-collar who actions the cart, with both hands up and down, at the end of the assembly line in the factory. His repeated gesture immediately activates the "mechanical" music that announces the end titles.
Second part of the "Trilogy of Neurosis" also including Investigação Sobre um Cidadão Acima de Qualquer Suspeita (1970) and A Propriedade não é mais um Roubo (1973).