A cast maybe necessary in your movie production.
If so, choose your cast carefully and ensure they can do the role. It is no use planning a cast and have some of them 'disappear' when needed on set.
Plan as few, or as many, in your cast.
Arrange for the cast to be there once only, for the rehearsals and the final production, done within the same day.
If there is no cast and your movie is more of a documentary, then you may decide to shoot a movie with a voiceover, which you need to narrate in a quiet setting with good acoustics.