This is a musical film with characters singing many known (mainly Russian) songs, with lyrics for some of them given in karaoke-type.
In one of the scenes, characters sing "Mama Liuba" ("Mama Lover") while driving the car. It's homage to the musical video of the song made in the same way. Olga Serebkina, who plays one of the characters of the film, is member of Russian musical band "Serebro" (which appears in the music video for the song) and co-author of the song.
Julia Alexandrova became a blond for this film to contrast with Olga Seryabkina. Then she simply liked to be this way.