If you’re talking about what looks like a ghost of a person, I’m pretty much positive its the result of a long exposure.
I can also tell that the photo was taken through a narrow aperture because of the starburst light effect.
I assume the person was walking and stopped for a few seconds long enough for the camera to record his image and continued on.
I like night photography and have intentionally created gohstly effects like that.
It also looks like there are some instances of the Sabattier effect, especially two in the crowd of spectators.