Unlock Nightmare Mode:
This difficulty setting will become available when you have beaten the game once.
Fast money, great hats & hidden winged sapphire all on Flynn's:
Go up to the tower in Flynn's ship and go to the place with the bear's shop and break the elemental gates then go up to the wooden doors and get the coins there should be about500-2000 then go to the end opposite of the ramp down you should be on the crow's nest there is a winged sapphire on it then if you have dragon engine put it on then go down and go to the edge of the boat jump onto the wing there should be a door go in it and talk to the dude you should see hats buy them.
First complete the game then go into the tower on Flyns ship.Go up the ramp until your above the bears shop there is a door go there you will get about 7000 gold go onto the first level when it says 10,000 go back to Flyns ship.repeat the same as last time this time you will only get 320 gold keep repeating.
Fast money and experience points:
First, you have to beat Kaos and have all of the elements. Then go to the tower part of the ship and go through the door at the top of the screen. There will be a lot of money and then go in the dorr at the bottom where Auric is. Break the elemental doors and get the money. Then go to Brock and do a challenge (it doesn't matter which one). Then repeat.