Union Flag being upside down has to do with whether the diagonals join the side or the base of the rectangle. It's not easy to spot.
The US flag is nice I guess, but the effect has been ruined by politics and how often it is thrust in our faces in television and film. From an aesthetic standpoint it would probably be nicer with fewer stars lined up just a bit differently.
The one I've seen for Greenland puzzles me, though. I mean, I GET the symbolism...but it just seems tht Greenland should have GREEN in their flag.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.