Extras and background performers are almost always needed in feature films to provide a sense of reality. In fact, one of the marks of an amateur film is seeing actors performing in empty streets. Even worse are scenes in which actors perform in crowded streets while pedestrians steal glances at the camera, wondering what's going on.
To avoid these problems, you will want to hire extras, also known as background performers. If you are a SAG signatory, you will have to comply with the SAG background performer rules that govern your particular contract. (See “SAG,” p. 205.)
Whether you are a guerrilla filmmaker filming your actors in a crowded city street or an independent producer who films all her scenes ...