Richter Warping Glitch
To activate this glitch, you have to be playing as Richter, and must be in the Inverted Castle Keep. Once you reach the Inverted Castle, advance to the left, until you reach the broken staircase. Using Richter's uppercut move (down, up + jump), jump up through the broken staircase. At the top, where the statues are, there will be a door to the left. Advance through the door. There will be two elevator platforms in the room. When you reach the top, take the door to the right. While going through the hallway, there will be risen platforms on the floor, and tombstones to fight through. When you reach the last risen platform on the floor, stand to the right of it, and push up. This will warp you back to the normal castle.
Never Ending Richter Fight
During the fight with Richter as Alucard you must equip the Holy Glasses and get both Richter and the orb controlling him close to death. When you have them both at low health hit them both at the same time to kill both at the same time. The easiest way to do this is with a bomb type item (Power of Sire, Pentagram, etc.) or it can be done with a regular weapon while they are close together. The battle will end as if you had only defeated the orb only you do not get the "Topsy Turvy" achievement and now you will fight Richter again if you enter the room again. If you defeat Richter again you will get the "Topsy Turvy" achievement but will be stuck in the room with Richter and Shaft as no cinematic starts up. To fix the glitch you must beat Richter and then exit with a library card and save your game.