Reflection and transmission of thin-film guided waves incident at various angles upon an abruptly tilted end facet are investigated using boundary integral equations called guided-mode extracted integral equations. The results obtained from this model are verified using the law of conversation of energy and are compared to previously published results. For oblique incidence, a variety of interesting phenomenon, such as guided wave equivalents of Snell's and Brewster's laws, are investigated numerically. These effects may be important in applications related to integrated optical circuits.