Bonus Rounds
There are three circular rainbow symbols that will let you play three bonus rounds if you find them.
In Stage 1, play the area in the lower-right corner of the map, directly below the red boss area. When you find Gogo at the far right side of the area, drop to the ground and go right past the rats to find the rainbow symbol.
In Stage 2, play the area that has the word "TINY" spelled out with carrots. Go past "TINY" and walk right to the edge of the cliff. Drop off the cliff and push LEFT to land in a hidden tunnel. Walk left and grab the 1-Up and Bell, then walk left again and drop onto the rainbow symbol.
In Stage 3, play the area that has the split waterfall. Play until you walk onto a ledge that starts moving upward. Jump off the ledge before you're smashed into the ceiling. Follow the tunnel to the left until you reach gray platforms. Drop down the platforms to a half-pipe with a rolling boulder. Walk left and jump into the wall on the left side of the pipe to enter a hidden tunnel. The rainbow symbol is at the end of the tunnel.
Passwords
Here are passwords for the first 13 levels and all the bosses.
Plains
Levels Passwords
1 KBGD LDLL LLLD DDDD LLGD
2 PBKL LLLD DDGD DLLL DDVD
3 YRBD LDLL DLKL DLLL LLND
4 - Boss QYBG DLLL DDBL LDLD DDTG
Forest
Levels Passwords
5 TYBK LDDD DDBG LLDL LDTV
6 HBBB LDLD LDBK LLLL LLTN
7 JYBB PDLD LDBB LDDL LDDQ
8 YMBB MLLD DDBB PLLL DDMQ
9 - Boss HMBB TLLD LDBB MDLL DDPD
Cave/Desert
Levels Passwords
10 KBBB TGDL LLBB TDLD LDNG
11 MBBQ HYLL DDBQ HGDD DDDM
12 KHBW HXLD LDBW HYDD DDDP
13 - Boss BRBW HXGD LDBQ HXDD DDGN
Boss
Levels Passwords
D. Devil BYBG LDDL LDBD DLDD LDTG
C. Coyote GRBB TLLD LLBB MILL DLPD
Plucky Duck XHBQ HZGL LDBQ HZDD LLGM
T. Revenger GJBQ HZZG LLBQ HZZL DDMR
Pirate Ship QJBW HZZB DLBW HZZK LLMG
Hamton KTBQ HZZQ WGBQ HZZQ QDVR
End Game PDBW HZZQ ZKBQ HZZW ZGJN