If you hadn’t noticed, the ghost is based on the old 1938 movie “A Christmas Carol”… 
A Christmas Carol
The black and white effect shuts off once the aliens are startled out of their charade.
I’m keeping with the theme that the aliens cosplay as important historical or mythological people.  Kinda like “Ancient Aliens” where everyone important happens to be an alien that our ancient ancestors mistook for gods or whatever.
So far, it turns out the aliens are Stephen Hawking, Santa Claus, and now the Spirit of Christmas Past! 
John Vogel