Since red, yellow, and blue are primary colors, they are all you really need. Also, those three colors mixed together will make your gray color for shadows.
Speaking of reflections:
It’s actually a myth that a mirror reverses your image. Your reflection is not flipped. What you see is the left-hand side of your face on the left of the mirror, and the right-hand side on the right, giving the illusion that your reflection is reversed.
However, a non-reversing mirror, or “true mirror,” was developed. It allowed the user to see their reflection as others saw them, primarily for applying cosmetics.
It’s easy to make a true mirror yourself—simply position two conventional mirrors at 90 degree angles, and look at your reflection from the join. A true mirror gives you a 3-D reflection which moves as you do, rather than giving you the flattish image you get in an ordinary mirror. It allows you to see yourself as the world sees you. Try it if you dare.
http://listverse.com/2013/12/30/10-crazy-facts-about-mirrors/