There is a hidden message after the Perseus boss battle. Stepping on the three white stars with Kratos' left foot and heading back to the tree directly behind the Reins of Chaos will cause Kratos to start absorbing red orbs from the tree. As this happens, a message will be written in the sky.

The message reads "Now I am become death, the destroyer of worlds." This is a line taken from the Bhagavad Gita, a piece of Hindu scripture famously quoted by J. Robert Oppenheimer after witnessing the detonation of the first nuclear weapon in 1945.
Contributed by DrakeVagabond
David Jaffe said that they did not want to include the Roman numeral number two (II) in the title because they did not view God of War II as a sequel, but a continuation of the previous game. However, they did not want the title to convey the impression it was an expansion pack.
Contributed by DrakeVagabond
Aphrodite is labelled as a character in the game's instruction manual, but doesn't make an appearance until God of War III.
Contributed by DrakeVagabond
The voice actor for "Bath-House Girl 2" from the sex minigame also plays the role of the mom in the Disney Channel family sitcom "Good Luck Charlie".
Contributed by DidYouKnowGaming