Health Increase
Collect six cages and you will increase your maximum energy. You can do this a maximum of 10 times.

Rayman 2-D Madness mini-game
Collect jewels during the game to get 1000 game points.

Racket Jump mini-game
Collect jewels during the game to get 3000 game points.

Crush mini-game
Collect jewels during the game to get 4000 game points.

Big heads
Press X, Y, X, R, L, Back, White.

Razzof Circus mini-game
Collect jewels during the game to get 6000 game points.

Keep powers with you
Stand on a can and your powers will stay with you.

Rayman 2 reference
In the Hoodlum's factory, get to the place where you have to jump across crates to get to the other side. Once there, keep going up. You will eventually reach a location with a switch to activate the lifts to get to this second "conveyor belt". On those lifts, get pretty well up to the top. There is a hole in the side of a huge "pipe". Jump and helicopter over there and go in. You will see some of the villains from Rayman 2, including Admiral Razorbeard and his other cronies.

Xowar Secret
Before you face Reflux in Tower of the Leptys, if you have 45000 points, where the 2 Knaaren rock carvings are, a door will open with 4 green gems at the top.