I feel the two groups that throw me off the most are the "older" characters and in he early games, the "younger" characters.

Alus from FFIII is only 10 years old was a surprise, Palom and Porom are 4. Stuff like that. I can't get over Cecil, Kain, and Rosa being 20, 21, and 19 cause I always thought they were in their mid-twenties. Cid Highwind looks older than his actual age while Cid Fabool looks older than he really is.