We present a study of Chandra's optical distortions by examining the positional accuracy of observed sources on the HRC-I. We investigate the Chandra mirror and detector models' ability to reproduce the detector locations of observed sources by simulating ~160 calibration observations of AR Lac, HR 1099, and LMC X-1. To study the optical distortions of the mirrors more directly, we compare a 63 ksec observation of the Orion Nebular Cluster (ONC) with positions based on the well-determined optical astrometry of the cluster. We simulate observations of 100 reasonably bright sources from the Hillenbrand 1997 catalog of the ONC and compare the simulated positions with their observed positions. Offsets between the optical positions and the observed X-ray positions help determine a map of the optical distortions of the Chandra mirrors.