when you stare at a bright light then look into darkness, images from the light can be burned or imprinted in your eyes. try staring at a light bulb for a few seconds then close your eyes or just look away - you will see shapes and distortions in your vision. this would explain the apparition on you bed after you turned off the t.v. as for the smoke alarm, sounds like the batteries were going bad and someone else in the house was annoyed by it and got to it to remove the batteries before you did.
