It’s a great question. Probably several I don’t want to remember. But one that comes to mind is wearing a tank top to immigration office when applying for extension. I knew better but forgot
Interesting that you mention that 'remember almost no airlines know that the visa exempt entry increased from 30 to 45 days'.
I'll be facing that issue in a few days when I fly out from LAX on EVA Air and have a return in 75 days. I have tried to contact the airline via phone and unable to reach anyone. And have emailed and Facebook messengered without a helpful reply.
So I will approach the check in counter calmly, smiling, and get there early enough so if I have to buy an 'onward ticket' I will be prepared.
I do have questionable confidence in airlines knowing the latest rules. Less than a year ago Japan Airlines was not aware that Ko Samui had the one-night quarantine scheme in effect and would not let me board my flight and delayed me till next day when I was able to get the 'proper' scheme to board.