Not that this directly addresses the shape of the earth, but a close moon (~3000 miles) is often associated with the overall theory of Flat Earth.
It is well known that two distant observers can estimate the distance to the moon using lunar parallax:
http://www.etwright.org/astro/moonpar.html
Parallax is the apparent shift caused by viewing an object from two different vantage points. You can see it easily just by alternately blinking your left and right eye. Parallax is also evident in the apparent position of the Moon viewed from two distant points on the Earth ... Read even more
