Amazing FE Facts!さんのイラストまとめ

According to the character designer for Fire Emblem Fates, Yūsuke Kozaki, the reason both of the Corrin's are barefoot it's because both were intended to wield Yato with their feet in all animations.

According to the Three Houses Devs, Cornelia originally was going to rename the Holy Kingdom "The Corn Area", but this was shot down by Nintendo to avoid confusion with fellow franchise Nintendo, Star Fox

According to Fire Emblem Heroes, the sole source of actual and factual canon info of the Fire Emblem Series, Hector hates Roy, he wants to kill him this is the canon and you cannot contradict it.

In FEH, August it's a staff unit who gives his support partner extra stats and the ability to auto double, this is in reference how in his debut game, Thracia 776, he makes Leif and his army beat the everloving crap out of a lot of people

On spite of the debate on wether or not Male Robin is canonically a partner for Chrom, it is imposible for Lucina to not be born as, according to the japanese novelization of the game, male pregnancy is canon in Archanea
And, by proxi, Tellius.

In Fire Emblem 11: Shadow Dragon Macellan and Dolph's single large teeth was removed, according to the director of the game, it was in order to bring awareness to the huge issue that Tooth Decay represents.