Ed-Edna double-team glitch

If both Ed and Edna appear in the third floor hallway while you're there and Ed gets to you first, Ed will start talking to give you a chance to give him something. If, before Ed finishes talking, Edna catches you, she'll take you to the dungeon. After that, you'll be able to freely move for a second before Ed takes to the dungeon again. Furthermore, if you give the exploded hamster to Ed right before Edna catches you, Edna will take you to the dungeon and then Ed will kill you from afar. This might be a frame-perfect trick.