I would like to elaborate on the question of what we can do within a 3 color-space.
As some people have answered, you can't really render exactly all colors with only 3 fundamentals, because the horseshoe diagram is not ...a triangle.
The problem concretely in the biggest spaces possible is to render correctly some colors at the fringe of the horseshoe, ...
As others have suggested the main culprit can you be the shutter lag because of the time taken to focus your subject.
You can reduce the lag by clicking ahead of your expected shot. Eg. If you are expecting to take picture of a person in air, press the shutter when the person starts to jump.