New Weapons:

Finish the game using arcade mode with the weapon indicated to get the new weapon when starting a new arcade game pistol --> machine gun machine gun --> Cane gun cane gun --> Shotgun

Get Arcade & Mirror Modes:

Finish the game 1 time to get arcade mode and Mirror mode

Get Hyper Arcade Mode:

Finish the game 1 time in arcade mode using shotgun to get Hyper Arcade mode

Get Mighty Joe Jupiter Trilogy:

Use cadet training mode and finish all Mighty levels. Complete those to get normal mode levels (Joe Jupiter Episode 2) and finish those to get Joe Jupiter Episode 3

Get Music Jukebox:

Finish all levels in the Mighty Joe Trilogy