As you may well know, there are a number of similarities between kingdom hearts and final fantasy. The most obvious one being the characters (duh!). But sometimes, they go deeper than that. 1. When Roxas (in deep dive) is fighting the heartless, he jumpes and starts attacking, first a heartless in front of him, and a heartless behind him. In advent children, Cloud uses the exact same move on Loz and Yazoo in their "secret" base 2. Before Sora falls asleep in Chain of Memories, he sees Kairi and Riku. These two are standing in the exact same stance, and positions, as Zack and Aerieth in Advent children. These are all I know so far, but feel free to share your own discoveries.
When Sora is mocking Leon when he first gets to Hollow Bastion, it's in a similar way to when Tidus mocks Maester Mika in Final Fantasy X. Same hand gestures too.
