Fun idea, but because there are only 50, it's tough to know which characters you've chosen. Maybe consider having small hints for each character? Also, there is a lot of type-in work needed. For example, "west," "adam," and "adamwest" didn't work, but "mayor" did.
What about Vinnie and New Brian as well as Doug (from Stewie's preschool)? Also for "Jonathan Weed" you should accept Mr. Weed since that's what Peter calls him. Otherwise a pretty solid quiz.