
Production Design
The set or location of a movie is very important, in Film Noir, it is usually located in urban areas, this means mainly the city, specificly dark streets in the puring rain, alleyways surrounded by garbage cans, bars full of people and cigarette smoke and detective's offices. This is all mainly at night.
Some of the props used are cars, cigarettes/cigars, drugs, money and weapons these are all necessary for the crime theme of the movies.
Costumes often showed the social class of the character such as long glittery dresses and fur coats for the Femme Fatale and trench coats with hats for men.
Lighting
Lighting was very important as they played with shadows for example the light outside coming inside through blinds and creating the strips of light and shadow in the room. Or the light could be quite dim or bright and this all adds to the atmosphere.
There was a use of low-key lighting, which created a lot of shadows to a character or a object, which created a lot of contrast between the black and the whites there were very few greys , they achieved this by using one small, intense light, this way the one light focuses on only one part of a object , leaving the rest in shadow, this added to the mystery and made the audience feel uncomfortable.
Sound

Sound was also very important as it provided the scene with a description along with diegetic sound, there also non-diegetic sound and this helps provide the mood, atmosphere and suspense. The music was jazz and piano music.
For example: As the hero of the story meets his enemy at a bar the music would be jazzy and low volume, yet it starts building up the scene, but when they draw their weapons and open fire the music become faster, louder, and more aggressive as does the scene.
There is also the very important use of voice overs, this is what allowed the audience to listen to people thoughts this allowed the audience to get to know the character, to hear their plans and solve the mystery with the character. The voice overs are usually used for the protagonist of the hero and they don't know what is going to happen. Throughout the film noir era as people played with voice overs the came across the idea to develop voice overs into things like hallucinations that show a characters psychological state.
Narratives
Narratives of Film Noir often involve some sort of downward spiral, that mainly focuses around the protagonist, theses were normally caused by a wrong decision by them and may have something to do with drugs, murder and money. Film Noir is often a whodunit type of narrative and are psychological.