Image creator here. This is such a massive dataset, most of the image processing needed to be custom written software pipelines. It not really practical for every pixel to be hand inspected. A few defects (and bright asteroids) imprinted through. It really hard to decide what is a real weird thing in the universe, and what is some sort of instrumental effect. We try to not pre-decide on what we think we should be seeing and filter for those by using things such as using classifiers. That leaves us with heuristics based on temporal information, size (is it smaller than a point spread function), and other related things. On large numbers of objects and pixels 1 in a thousand or 1 in a million outliers are bound to occur.
I'm glad you responded (i'm assuming you knew i wasn't criticizing the effort, but just in case -- I wasn't). I was assuming asteroid trail, but I've read that green stars can't exist and _could_ be a technosignature of "little green men". :) Your work on this is lovely. The combined effort of so many smart people over decades of work is truly heartening. Thank you.
