Wii Special Featuers?

Really don't know where else to ask this.
I have the game on the Wii, and just finished it.

On the back of the box says:
-All 5 episodes of Back to the Future: The Game
-Complete Behind the Scenes video series
-Full production art gallery
-Video reel with hours of audio commentary

Apart from the 5 episodes of the game, which I've finished, where is the rest?
I thought another menu might appear on the title screen after I finished the game, but I'm not seeing it. Any help would be appreciated. Thanks!