Board Thread:Sly Cooper: Thieves in Time discussion/@comment-76.179.159.25-20121211225104/@comment-4356024-20130107155744

I think it's possible that they've either left out episodes (for DLC purposes), or left them to be unlocked through various means (clue bottles, masks, etc.). Wouldn't that be a kicker? They wouldn't show secrets like that in a debug menu, and DLC is pretty much confirmed in the livestream ("surprises" are, specifically). They also tended to steer away from the inevitablity that there were only five core-worlds when asked numerous times, even in roundabout ways (like how the costumes were to correspond to each episode).