before people jump all over this, I watched the 
movie in realmedia format (which is where the 
screencap is from), so there were a lot of frames 
lost.

Gohan maintains this pose through a 
transformation to SSJ-4604, or a powerup or 
something, during which there's a special effects 
flash, which darkens Gohan's figure because 
there's a blast of light around him.  If the cel 
is from anywhere, it's from that part, but like I 
said, I saw the .rm file so there were a lot of 
frames lost, so I couldn't tell.