Time for a bit of geometry and optics:[list=1][*]There is a triangle between your eye, the moon and the reflecting spot on the Earth's surface[*]The sum of angles in a triangle = 180 degrees[*]The angle at the moon is something close to 0[*]Looking down say 10 degrees makes the angle at the Earth's surface close to 170 degrees[*]A ray reflecting from a "flat" surface meets and leaves the surface at equal angles[*]Those angles would be approximately 5 degrees, actually quite close to half the angle down from the viewpoint -- cockpit, mountain top, tower...[/list=1] Those who have better maths recall can apply height above the ground and Earth curvature to determine the position of a tangential reflecting spot.
The size of the moon and atmospheric diffraction will yield a reflecting spot of considerable area as well as a small spread of angles as rays from different areas of the moon radiate and merge with other rays.