Leave game boundary
On level 1 when you get the first key, go through the first gate. You will see groups of ants marching. Allow them to see you, then roll up to a wall of grass on the side of the land. Let the ants hit you, and if you are lucky, you will fall through the wall and get on the other side. There will just be a path going around the border of the land. In the background you will see faces. After awhile the game will return to the menu screen.
White screen
On level 3, take the second Taxi Bug out to the farthest point that ends in the water. On the right is a rock. Push the Taxi Bug so that it can go through the weed. Position it so it is slanted in the weed, facing somewhat off the rock. Get off the Taxi Bug and walk on the long narrow rock. Follow it until you can jump into a white world. There is nothing there but whiteness. You can roll on forever.