Look at the MFDs. You can see background detail thru the MFDs. That is because the MFDs are transparent and are projected upon the pilot's helmet visor.

As a result, when he is looking thru the HUD, the MFDs appear lower down and overlay the instrument panel...that is why you see the attitude indicator, for example, behind the right MFD....next to it, the compass is seen as the green circles.

Also, note that the TI/IRST is not transparent.