It's been a year since P.T. was released, and players are still finding things which many may have not noticed.
Note there are spoilers below, just in case you don't have the demo installed and decide to give it a go at a friend's house someday.
Apparently, the demo's ghost Lisa can be seen in a room in the basement. This is the starting point for the demo.
Proof of this was posted by Reddit user metatronicsauce who shared a screenshot of the ghost in the "talking paper bag room".
According to the explanation, once the player gets trapped in the bathroom, becomes possessed and is killed by the ghost, the player will be transported back to the starting room.
“If you exit the room backwards, you will see Lisa very briefly before you enter the hallway," said metatronicsauce.
More evidence was found by unitedplayersclub who posted a video showing the scene described above. It's below.