I couldnt find much on what the Spandaus flashes would have looked like....So I just guessed based on actual small caliber muzzle flashes. They come in a few common shapes. I dont know about the use of traces durning this fight. I bet someone here does.
The "trigger" as seen the blue max was only done so as to give the movie goer a visual que that they were firing their guns. It's not accurate.
hth