Extra Lives
Enter XGT8QL as a password. When you get to the part of carrying bananas to two monkeys, distract the second one, bust open the crate behind him by holding B, and run into it. There should be a horseshoe in the same location as the crate. Walk over it to get an extra life. You can do this as many times as desired.
Passwords
Enter SBM2S6 as a password to start falling getting stars.
Enter the following passwords to start at various points in the game:
JBR!S6
SLRZQL
JQR2SN
DLC2S6
NBR2SN
NGH2S6
NBC2SN
SG12QL
GJ?4L6
Enter S8MXS6 as a password to start at about the middle of the game.