A Martian Arrived on An Autumn Night(1980)

Original title: Прилетал марсианин в осеннюю ночь

Pashka Girya and Valka Komarov, cadets of the school of military musicians, tired of strict discipline, ran away to the south. Having experienced a number of adventures and meetings with interesting people, the heroes judiciously assessed their deed and returned to school.