In Dante Alighieri's the Divine Comedy, Dante and Vergil happen across the Cerberus on the third level of hell. Dante encounters Cerberus at the end of Mission 3 in the game.
The opening cutscene for every mission contains a number which represents the mission number. For example, the pizza box from mission one has a '1' printed on it, the '2' on the billboard in mission two, etc.
Rebellion was the key to unlocking Dante's "Devil Trigger." Sparda enchanted the sword to react with Dante's own blood in order to bring out his power. (Prior to his battle with Vergil, the eyes of the skull on Rebellion were closed and the bottom of the handle was just a pointed edge. But after the battle, the eyes blowed and the bottom of the handle was opened.)
Though the blade Force Edge and both of Sparda's amulets are featured in the game, the 3 are never joined to create the sword "Sparda." (Which would bestow the wielder with Sparda's latent powers.)
As trailers for the game reveal, the pool table in Dante's office was changed from a green to a red one at a very late moment in production