Sorry for the bump but I think I might have found a bug in the level Ruby Cavern on the vanilla version. When you get into the room where the key is, there appears to be no way out. I can't go in the pipe or anything.
Screenshot of the place if it's needed:
Edit: I've tried all those yellow pipes there just in case they were special and I also tried the pipe you enter from at the bottom. I've also tried getting up on the ledge in the upper left and there seems to be nothing there either.