When Lou returns to Burton's dojo a window has been broken and she collects the glass up from the sidewalk. However, if the window had been smashed from the outside, the broken glass would be inside the building, not in the street.
The NYC establishing shot (41:55) features a Statue of Liberty with the replacement torch from the 1980s.
When Winston enters the basement underneath the dojo, Lemmy is toting an FN MINIMI Mk 3, a light machine gun first manufactured in 2013.
When the goons show up at Uncle Charlie's (Peter Greene) place the are driving 80s models Chevy Suburbans.
The two-handed thumb forward pistol grip wasn't used back in the seventies.