This may not be a bug, but since I can't find any switches in the Mausoleum of Queen Lyriden to open the 2 secret doors, I'm thinking that the solution to have them open is to eradicate all of the flying skulls. However as it stands, there is one skull on the left side of the screen that is not reachable by the main character and therefore, this cannot be completed. I've attached a screen shot of the skull in question. The spot in the pic where the skull lands, the character can not be placed there.