Maurice LaMarche based the voice of The Brain on Orson Welles. LaMarche also later played Welles by dubbing over Vincent D'Onofrio's voice for Ed Wood (1994).
Beyond these doors is an agony worse than all others. You will remain in here for eternity listening to... whiny protest songs from the Sixties.
The show is over - Go do your homework!
When the show reran on Nickelodeon and Nicktoons almost all references to Warner Bros. were removed from the opening. Allowing a very unusual transition involving the Nickelodeon logo bursting and the opening cut right to the WB water tower open.