A nice list of easter eggs to be found in The Legend of Zelda: Twilight Princess is making its way across a few forums on the internet. On the IGN Boards, user yoshi117 posted a list from another forum as compiled by someone named Ecurevil. When a game is in production as long as Twilight Princess was (it was first announced in 1864, I believe), lots of great details are bound to spring up. A few of my personal favorites are below. Got any others? Post them in the comments!

List of Twilight Princess easter eggs (IGN)

• The night sky is an accurate representation of the real night sky. Stars are the correct brightness, and constellations such as Orion and Cassiopeia. The moon moves, but the stars stay still, however.
  
  
• When you open doors in a dungeon, Link opens them himself for the first time in a Zelda game. Dirt will fall off of the door the first time, but will be clean all times after that. Nice attention to detail..
  
  
• Ooccoo is the little bird that warps you out of dungeons. 00CC00 is the hexadecimal colour code for the green of Links tunic in the original Zelda. It's likely a coincidence, with Ooccoo being a play on Cocoo (the chickens).
  
  
• Fyer (the cannon guy) has a bullet bill on his sleeve.
  
  
• When you ask the fortune teller in Hyrule Castle town for your 'love' fortune, her chant is actually "Wait....loading takes a while" spelled backwards.

Source: Nintendo Wii Fanboy