Tangentg

So it was a glitch in the original and an Easter Egg in part two? So you mean, by leaving a last big invader on the screen you could get a point bonus? I was trying to read up on this but I couldn't find anything.

Yep http://www.digitpress.com/eastereggs/arcadedeluxesi.htm

But the rainbow effect shown in the picture doesn't resemble the trail/afterimage one I was thinking of...