The Flash "Kind of" Double Exposure

Most of the time I pre-visualise my pictures. I scout out locations at the time of day I want to shoot and make some test pictures, so I normally pretty much get what I planned. Not so in this case.

The picture was taken on the palm Island on a spot where I could have a nice silhouette of the Atlantis Hotel at sundown. The basic idea was, to shoot a model with an antique car , a Bentley S2.





The plan and most of he pics were something like this.





I wrote before that the sun moves fast fast fast near the Aequator and there is not much time between sunset and darkness. So I had to constantly dial up the time to keep the background from becoming pitch black. After a lot of shooting the Owner departed with his car and I started packing up, when the Model suggested a few more shots without the car. OK.

With the car gone there was space now an she started to pose and jump.
The flash set up was a SB900 on Camera for fill and as a master and three Metz 45er into one large shoot through umbrella. (Three 45er seem to be overkill, but we started out with a lot of ambient light and I needed the power then. Later I continued with two, just switched one off.)

The picture above was actually the last frame shot at that day.

I like it a lot becaus it looks like a wild multiple exposure. It was in fact just one shot.

What happened?

Obviously the Hotel switched on the lights.
The sky was still relatively light. (In the direction of sun down.)
The foreground was already completely dark.
The exposure time had crept up to 2 seconds and I shot hand held.
The foreground is illuminated by the umbrella cumming from left behind me.
As it's ambient light level is very dark the picture looks like a single exposure.
The jump is kind of frozen in this part of the picture.
The sky and the lights from the hotel are bright in relation to the flash exposure (f 14).
That's why it looks like a double exposure in this parts and the jump has movements.

I was totally surprised by the result, but it can be mostly explained.

But look at the "shadow". If you observe closely you will notice that it is no shadow at all. Because it is not actually on the ground where it should be.

Frankly I havn't figured out a good explanation.
There is one more picture for you below. let me know if you can explain the shadow.