Unification of koreas unnecessary,
Professor was not smart but other characters were shown dumb,
FL was dumb for being an elite officer,

she let ML get away not once but multiple times and at end she isn't Arrasted already, she is allowed to leave country during inquiry
there were enough evidence that she was dating leader of Terrorist group and let him get away many times, but she is free to run away because she doesn't have money in her account, suddenly police forget that she was dating him and she was getting paid in different way then money,
In normal case she would be frame for everything and her husband would have gotten custody of there daughter by claiming that this woman is a terrorist.
but No FL is having a normal life even after helping a robbery, and even allow to leave country during her investigation to meet the Criminal and her husband is not doing Anything against her..

2nd big problem of drama,
US ambassador don't do anything then one dailogue with Assamblymam,
Ep 4 of part 2 shows that it was public that Assamblymam Kim order killing of Anna kim but US ambassador doesn't even show up in drama again do not do anything
korean assambyman try to kill US ambassador's Daughter
we all know that US has full control over South korea and also have a military standing there and US ambassador and US government did nothing when they hear that korean assambyman is trying to kill one of there citizen moreover daughter of a high level diplomat

after ep 4 US army would have taken control over that and as we all know US Marine Corps Navy seals is far more better force then So called Korean SOU flower boys