To add a piece on to the bad ending you have to make sure your money total is $0 by the end of the game. Playing under normal mode and not getting any adapters may also help. Buy a cake and mojo doll to waste the money collected after a country. Also waste a cake before defeating the Boss. If money is accidentally collected, fall down a pit or do something else to start again (usually from Launchpad or the Boss). When the game is completed with a $0 total, you will see Glomgold titled as the greatest adventurer.
Finding the map pieces
Bermuda
After all the water and rings, go up one screen and then left. Pull on the ring and proceed. Pull on the next ring and jump on top of the raised block. Immediately pogo jump off the block on top of the column. Now, pull the barrels toward you with the switch, then pogo off one onto the conveyor belt. Then, jump to the treasure chest containing the map piece.
Niagra
There is an iron box near Webby. Pull it to the ledge to go on top of it. Then, go on top of the chest and golf swing the invisible box. You can now go in a room containing the map piece.
Mu
At the beginning of the level, break all but the last round rock near the large one. Golf swing the last one and the large rock will come loose. Pogo jump off of it and head to the next one and loosen it. Do not break the ones on the floor. Then, pogo off the rock to the ceiling that was behind you. Head across the ceiling to a rope. Climb up and you will reach a clearing and eventually find the map piece ahead of it.
Egypt
There are two square rocks near the beginning. Hit them and go down the waterfall that was under them. Go on top of the last rock to create some waterfalls that you can move on. At the end are some numbered blocks. Pogo on #3 twice, #1 four times, and #2 once. The wall will open up to reveal a map piece.
Scotland
The first time that you climb up a rope, go left. Bounce off the hidden treasure chest next to the wall on the floor above (first hug the wall and jump to see it). Break the square rocks in this hidden area and enter the wall in this place where spears are sticking up. You will find a treasure chest. Break it and fall down the fake floor that was underneath. Hop on the block with an arrow on it and go on the ledges that are appearing. Climb the chain and to get the map piece. Note: You will need the Iron Adapter to get to it. You will transport to the basement, unless this is not your last map piece. (In this case, you must exit through the ceiling to the left of where you are presently located.) In the basement you will find the Secret Treasure of McDuck and a new ending once you defeat the D-1000.