In the cave with the bubbles going up, you can pass through the east wall when launched properly by the bubbles. Unfortunately, you fall down to some place you can't see your character (even with the flashlight) and have to stumble around trying to find out why you are there.

Is there anything there, or is this a complete glitch?

Also, is there a good walkthrough for this game?

Not what I'd call a standard walkthrough, but this helps a lot.