Here is a guide for the how and when of special notes in screenwriting.
A Different Framework
The difference in screenwriting over other narrative forms is that it is up to someone to interpret it into a literal medium later. What that means is that in terms of spatial and story reality, you have to have someone understand what you are trying to convey.
To do this, you often have to go outside the standard format set forward by the screenplay and offer even more text to clarify something. Though some people use the “creative" and indulgent author’s intrusion in their screenplay to do this, it is still not preferred. Instead you may just want to include a special note in your screenplay.
When To Use Special Notes
A special note in screenwriting is where an idea or clarification is included in your script that cannot fit anywhere provided by the scripting format. This is usually a reference to the director about something that was intended by the screenwriter, but is not overt in the screenplay. This can be something about how the character’s should behave, the way the set should be, the connotation of some action, the quality of the film stock during a montage, or pretty much anything that the screenwriter think that the director and producer absolutely must know.
There is really no absolute limitation for what can be included in a special note except what you feel would be not well received by the professional party you will be working with. If the special notes are too excessive or too direct and would take away from the director’s creative voice, then they should be cut down.
Special Note Format
When you are using a special note, they will usually come directly after the event you want to comment on. This can happen after a sequence or scene, but usually after a significant chunk has gone. You then indicate that it is a note and keep it in parenthesis. Example:
(NOTE: Though the character is explaining the rules of blackjack, and you will be able to pick out the details at times, he should be talking too fast for most people to understand the entire thing. You then use a CUT AWAY to show that the other characters cannot understand him either. This way the audience knows that they are not intended to understand everything.)
This special note would then go at the end of the monologue of the other character, yet indicate something about the speech that would not be clearly enough indicated by the actions of everyone in the scene.