Beat the pilot Z.O.E in mission 19 to access mission 20. In mission 20, do not shoot down the cruise missile, and you'll unlock the bad ending of the game.
In mission 20, shoot down the cruise missile to advance to the bonus mission: Fighter's Honor. Defeat that mission to unlock the Bonus Mission.
You must destroy the C-5 transport on the first raven level in order to unlock the hidden mission level.
Make your way to the 19th mission ''Kingpin'', and beat the mission without destroying the skilled enemy pilot Z.O.E
Press and hold Square during the replay to pause the camera during the mission replay.