Here is a flag that breaks a few rules.
That is the Canadian Red Ensign. Though it was never officially Canada's flag, it was flown above the parliament buildings for many years and was used to represent our military over seas. I personally believe it is truly beautiful even if it does break many of the rules outlined in the OP.
The color red in the background of the flag symbolizes life and blood -- blood shed in the settlement of this country and in wars to preserve basic freedoms. The Union Jack is rather self explanatory. Canada was founded with strong ties to Great Britain. I won't get into the explanation of the Union Jack. Needless to say, it has tons of symbolism. All of which was translated into this flag as well.
The Canadian coat of arms is on the right side of the flag. This is the element of the flag which breaks the rules seeing as it is so detailed. It speaks greatly to Canadian history. The crest contains three maples leaves with stems joined. The three leaves represent the component peoples of Canada: the natives, the French and English original settlers, and the others, mostly European, who came later. The veins of the leaves are gold, symbolizing wealth -- wealth created through unity and passion for this land and hard work. The Maple Leaf, of course, also represents the forests of Canada -- a most important contributor to the nation's wealth.
The emblems within the crest reflect the origins of our founding peoples. the couchant lion (upper left), emblem of William of Normandy, has been used by the British monarchs since 1066. It represents both the British and French settlers. The red lion rampant (upper right) was the emblem of the Scottish monarchs. From Cape Breton to Glengarry County, Ontario, Scots, many refugees from the Highland clearances, were important early settlers and leaders (like Sir John A. Macdonald) in Canada. The harp (lower left) is a symbol of Ireland -- another important source of our founding people. The fleur de lis symbolizes the early French settlers of Canada, who brought this as an emblem of a royalist not a republican France.
I didn't intend for this explanation to get so long. As you can see the flag holds more symbolism that most. Being a Canadian, it means the world to me. Just goes to show you that even if a flag doesn't follow the rules, it can still hold just as much (if not more) meaning to those who reside under it.