The Fermilab Main Injector is a new 150 GeV proton synchrotron, designed to remove the limitations of the Main Ring in the delivery of high intensity proton and antiproton beams to the Tevatron. Extensive studies have been made to understand the performance of the Main Injector. In this paper, we present a study of the Main Injector lattice, which includes magnetic and misalignment errors. These calculations show the Main Injector's dynamical aperature being larger then its design value of 40pi mm-mradian at injection. We also discuss a correction scheme that reduces the effect of these errors on the performance of the Fermilab Main Injector.