Stack It
You can stack up multiple items by carrying one, jumping onto the other, and then dropping the first one. Then you can carry both at the same time. If you want to unstack them, just throw them with the Kick button.

Camera Reposition
The camera can be repositioned when you find your vision blocked. Use the L2 and R2 buttons to swing the camera left and right.

View ending sequence (PAL)
At the "Era Selector" screen, hold L2 + R1 and press X, Square, R2, L1, Circle, X, Circle, Square, Circle.

Full carrots (PAL)
At the "Era Selector" screen, hold L2 + R1 and press X, Square, R2, L1, Circle, X, Square, Square, Circle.

All levels (PAL)
At the "Era Selector" screen, hold L2 + R1 and press X, Square, R2, L1, Circle, X, Square, Square, Square.