The general relativistic effects on light propagating through a space which contains an inhomogeneous distribution of normal matter and dark matter may affect our interpretation of observational results. In this talk, I will examine some observational aspects of dark matter and dark energy. I will discuss a numerical simulation in which we have derived a scheme to include general relativistic corrections for general inhomogeneities in normal matter and dark matter. In particular, the supernova magnitude-redshift relation will be examined. It has been proposed that this effect of local inhomogeneities may account some or all of the the apparent cosmic acceleration. I will discuss current limits on this possibility.