Chihuahua spots strangers INSIDE my house at night!

I was in bed last night & all of a sudden Tippy’s hair on her back raised up and started barking & wouldn’t stop. I finally leaned forward so I could see past the door to see what she was barking at bc it was starting to creep me out. Lol. I thought I had turned the TV off before I went to bed, but apparently didn’t and the slideshow of our family pictures was flashing on the screen. She thought the people on the TV screen (pictures of us) were real. Lol. Had to go turn it off. So funny. Dogs are a mess, especially chihuahuas!