Previous work has shown the existence of some structurally forbidden reflections in the electron diffraction patterns of (100) oriented polycrystalline films. These films were deposited under ultra‐high vacuum conditions. A continuation of this work has resulted in the observation of these and other forbidden reflections in the diffraction patterns of two other kinds of films: (001) oriented single crystals containing deformation twins and (100) oriented single crystals. The existence of these strong reflections is probably due to strong dynamic interactions between the electron beam and the crystal lattice.