Here is a list of where all the bonus rooms are.
game: LEVEL- red balloon
Right-hand wall in the pit under the tree with The "G" icon. It's just
after a big hill or just about where the first bonus room exits, if
that route was taken instead.
game: MATCH- Rambi, Expresso, Winky, Enguarde icons
game: LEVEL- "n" icon
Low off-screen barrel cannon, just left of the red arrow (showing the
end of the board.
(Fall into the pit just before the red arrow sign)
game: FIND- red balloon
game: LEVEL- red balloon
Visible barrel cannon above and left of a "DK" barrel on a hill,
between the "K" and "O" letters. (The barrel cannon is only visible
when standing on the hill. There is a second similar hill after the
continue barrel, which does not have a barrel cannon nearby.)
game: LEVEL- only bananas
Right-hand wall of two-"Slippa" pit, just past the continue barrel and
the "N" icon.
game: LEVEL- only bananas
game: BLAST-SIDEWAYS- DK barrel and red balloon
Right-hand wall of the pit that is between the 2nd and 3rd
purple"Kritters" after the continue barrel.
game: BLAST-UP- top off-screen prizes: Enguarde icon on the left, red balloon in the center, and a bunch of bananas on the right.