It's impossible to get everything right, but a flag isn't easy to fuck up unless you're just not giving a shit.
Oh good lord. At first glance it appears symmetrical as someone said but after you read about it - it's not. It's not as if to the casual American
viewer or even someone who's a skilled American
director that such a thing would be obvious whereas I'm assuming even to the most inexperienced British director hanging the American flag upside down would be an obvious and stupid mistake unless they were trying to make a political point.
I'm doubting that Abrams thought having special production people on staff to make sure the Union Jack was flying in a few frames right was worth the cost and no one in pre and post production caught the mistake.
If anyone deserves blame here it's set design not Abrams.
Oh and BTW, why didn't Benedict Cumberbatch who is a British actor
catch the problem when they were filming it?
Mickey Smith from Dr. Who is another famous British actor who was cast in some of the scenes where the flag is flying.
They must not be patriots?