The saltires on the Union Jack are wrong. The St. Patrick's Cross should have a width of 2 and the whole saltire should have a total width of 6 (1 fimbriation, 2 St. Andrew's Cross, 2 St. Patrick's cross, 1 fimbriation).

The fimbriation between the St. George's Cross and the field is also wrong. The cross should be 2 fimbriation, 6 St' George's Cross, 2 fimbriation.

These numbers are for a Union Jack that is 60 wide and 30 tall (1:2) and for a Union Jack that is 50 wide and 30 tall (3:5).

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The Japanese flag is also wrong -- done properly, the flag is 15 wide and 10 tall, and the Sun has a diameter of 6. In this pic, the Sun's diameter is considerably less than three fifths of the flag's height.