The world is actually a hidden world; if the player has collected all Power Stars troughout the game, they will access Heinous HQ; if (s)he didn't, SMG3's Tower serves as the final stage and Dark Star X9 serves as the "final boss".
-1: Interfere not Found
-2: Operation DigiCrash
-: VS. Bowser and Bowsar
-3: Random Chase Scene
-4: Afraid of the Awful...
-: The Power Stars Do Not Know Any Better
All enemies previously encountered in the game
Koopalings (as sub-bosses)
Crazy Japanese Guy
Heinous HQ resembles Deep Core from Sonic Rush Adventure, Hyper Zone from Kirby's Dream Land 3 and Dark Star from Kirby 64: The Crystal Shards in several ways:
All four need to be unlocked by collecting an amount of objects/items (Power Stars in Super Mario 64 Bloopers: The Videogame, Crystal Shards in Kirby 64: The Crystal Shards, Heart Stars in Kirby's Dream Land 3 and Sol Emeralds and Chaos Emeralds in Sonic Rush Adventure).
In all four territories, the true final boss(es) of the game is/are fought (SuperBowserGlitchyKing in Super Mario 64 Bloopers: The Videogame, 0² in K64: The Crystal Shards, Zero and Dark Matter in Kirby's Dream Land 3 and Ivo Robotnik and Dr. Nega in Sonic Rush Adventure).
This is the game's only world to have less than four playable characters (only Mario and Crash Kandicoot have access to the levels, Mario only to Random Chase Scene and The Power Stars Do Not Know Any Better).
Heinous HQ is the only world in Super Mario 64 Bloopers: The Videogame to have different sections, areas, biotopes and biomes (not counting SMG3's Tower's differently-based rooms and chambers).
Heinous HQ has the most hazards, enemies, bosses, mid-bosses, sub-bosses and areas of all worlds in the game.