The law of reflection does not hold for diffuse reflection. Here, the light does not bounce back as a ball thrown against a smooth wall, but bounces back in an arbitrary direction. The similarity between diffuse and specular reflection is that the light bounces back instead of passing through as it does for refraction. A mirage is the result of refraction of light through the air close to the ground. Every time you go down a road in the summer here and see the forever receding puddle of water you are seeing a mirage.
Stars twinkle due to many changes in the density of air between the observer and source.
The changes are due to differences in temperature and refract the starlight so that the observer sees the effect of a prism. The result is a change in direction of the light. Light bending in an optical fiber is really a combination of many small straight lines as the light bounces via total internal reflection off the insides of the optical fiber.