A number of these facts fit into the "easter egg" category. Developers will often put inside jokes into what they are working on, or use something as a reference point, and create around it. Projects have code names based around a common name, like gods of Greek mythology, tree types, or planets. This goes beyond just games to. One example of a noted industry inside joke is the Wilhelm scream. It is a canned yell that guys making movies have used over and over again.
Here is more on the Wilhelm scream: http://www.youtube.com/watch?v=_PxALy22utc
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