There's a pretty cool Vidsauce video on this. The most popular version of the map that causes this misperception also causes Greenland to look much, much larger than it really is.
http://gmaps-samples.googlecode.com/svn/trunk/poly/puzzledra...
Also, I'd suggest any how or why enthusiasts on HN to subscribe to Vsauce (if you aren't already). It's just amazing.