"빨강하고 하양하고 파랑"
Translation:Red, white, and blue
And Korea (North and South), Australia, The UK, France, Cambodia, Chile, Costa Rica, Croatia, Cuba, Czech Republic, Dominican Republic, Haiti, Iceland, Laos, Liberia, Luxembourg, Nepal, Netherlands, New Zealand, Norway, Panama, Paraguay, Russia, Samoa, Serbia, Slovakia, Slovenia, Taiwan and Thailand. I may be missing a few.
If anyone is for some reason interested, North Koreans prefer to use words 붉은 and 푸른 for red and blue respectively when referring to their flag.
I think if you were using the above phrase to describe a noun, yes, I believe your form would be more correct but since all we are doing is listing the actual colors the phrase is correct.