I love this game and I wanted to see if there were any levels that I might have missed, so I started looking at the ROM and now I feel like I can make some headway into a stage/level viewer...
TRY THE VIEWER NOW:http://www.gingerbeardman.com/pangds/
Extract stages tile maps from ROM
Find object (player, balls, power-ups, ladders, gates, etc) placement position data http://www.romhacking.net/forum/index.php?topic=23992.0
This seems to be one of the test levels that is not playable in the game.