The Ultimate Screenplay Format Reference

Notes

You shouldn’t write anything that’s only meant for the reader. Every line of narrative should translate into shots that end up on the screen. Don’t write what people think or feel, don’t talk about the past. In the narrative avoid smart terms that only a few readers may understand.

That said, you might encounter a situation where you have to tell the reader something - or you think you really have to in that particular situation.

In this case Trottier suggests to write the note in a separate paragraph. Here the example he gives:
 

(NOTE: This scene is shot in BLACK AND WHITE. It should appear old and scratched as if it originated from a 1950’s publiuc information library. There are intentional JUMP CUTS.)
 

Even here the question arises: Why demand BLACK AND WHITE. Does the story really depend on it? But we’re not going to argue with Trottier here, right?

To give you an idea what you may experience when you decide to write a note to the reader, here an example I made myself with professional feedback.

In my script something was happening in the middle of several characters present in the scene. However only one of them could see it. I constructed the narrative so that from the visuals that should be clear. However, I just wanted to make sure the reader gets it and thus wrote this:
 

(NOTE: Only Janet sees the light.)
 

Reader’s comments: How will the audience know this? Need to have her reference it in order to make it clear, because audience won’t have the privilege of this note.

The reader is correct. The note’s purpose cannot be to tell the reader something the audience also needs to know and has no way of getting it otherwise. But her referencing (mentioning) it wasn’t practical and after checking the narrative again I found that it was clear enough. So the next time I wrote this:
 

(NOTE: As the visuals suggest, only Janet sees the light.)
 

This time the same reader suggested to append ‘which only she can see.’ to the narrative and scratch the note.

However, another reader said: “If the visuals suggest it, you don’t need to write it.’

Great. You can’t win, I guess.

Whatever, all this won’t kill your script. If things like this happen to you I suggest picking one option or drop the note entirely and then focusing on the story. That’s what really will make or break your screenplay.