With freelancer it was not easter eggs, but things that Digital Anvil scrapped because Microsoft got sick of waiting. I mean the game took 5 years to put together.
So a lot of stuff is in the code, but DA wasn't able to develop it fully, so it was left dormant.
Things like NPC's using bats and bots, that was in the game, modders just needed to flip a switch to make it work.
And the shields, the Adv Champs aren't buyable anywhere, and neither is the higher level light fighter shields, but they were in the game.
Basically DA had their master idea of what they wanted to be, after all the Roberts brothers defined the Space Sim, but Microsoft got sick and tired of waiting for the masterpiece, so they did what they could and left the rest in their unconnected. Basically left it sitting waiting for modders to find it.
Hmm, where have I come? Why does it seem so familiar to this one?