Here is an interesting comparison of Cortana over the course of the 4 halo games:
PTesh adds his dulcet prepubescent tones over the top of one of the new trailers for weapons...
Try upgrading your browser to Google chrome (you wont regret it). There is probably an IE...
Teddy Bear Backpack
At the begining of the level, just before you enter the first building you will see this Teddy Bear Backpack amongs the dead civilians outside. The backpack can't be used, or equipped, but can be moved with grenades and weapon fire. Bungie loved to make easter eggs with teddy bears and there are still more to be found! :)