Unlimited lives:
Eat a ghost on maze 1, two ghosts on maze 2, three ghosts on maze 3, and four ghosts on maze 4. Then, press Up, Down, Up and intentionally lose a life.

Move through walls:
Enter the warp tunnel and quickly and repeatedly press Up, Down while inside. Make sure Down is the last direction pressed before re-appears to wipe across the screen. You may move up and down through the walls, but will not be able to move from side to side.