One of the first scenes showed to the press involved what was intended to be a part of Pandora's temple where Kratos has to stay on a magic elevator through an outdoor environment while a roaring sandstorm prepares to hit. The game play mechanics were finished, and the level was almost entirely completed but the sandstorm effects just turned out to be impossible and the whole sequence ended up cut.
Kratos went through numerous different incarnations of armor, however the designers felt that the more armor was stripped of him the more brutal he ultimately became.
Some of the concepts teased in the game's unlockable bonus videos were used in God of War: Ghost of Sparta, such as Kratos searching out his mother, or the video about what happened to his brother. However they differ slightly in Ghost of Sparta.
The Oracle of Athens is wearing 21st century style underwear under her dress. This may be because the underwear of the time period was too revealing, and the creators wanted to keep an M rating.
What are the differences between the Censored European Version and the US Version?
A
Since the game is pretty violent, it faced some problems for the European release - therefore it had to be censored a little bit. For instance in the sacrifice cutscene the soldier was repleaced by a zombie in the European version and therefore the scene isn't that crude in the European Version. A detailed comparison between both versions with pictures can be found here.