Courage
Mulan is an exceptionally courageous young woman; even when she has the chance to escape danger, she stays and fights, looking danger squarely in the face and staring it down on most occasions. Although she gets disillusioned and depressed after seeing so many of her friends killed in action, and wants to give up the army and go home, this is not out our any lack of courage, but out of love for her friends and an inability to act in an emotionless way. Mulan actively puts her soldiers in the less dangerous or threatening positions and takes on the more hazardous roles or campaign positions herself.
Mulan's courage stems from love; she loves her father too much to see him conscripted into the army again when he has served twice already, and when he is ailing. She joins the army in his place which is a courageous thing to do. She quickly rises to the top and takes on the most dangerous roles. She is also not afraid to be executed if it means keeping her father's good name intact, which inspires her to falsely admitting that she stole a pendant in order to avoid being discovered to be a female, which would bring shame on her father. She also fights the enemy with courage and leads her troops from the front.
The other key "good" characters in the movie are also blessed with more than average courage and all display great leadership in leading by example not just by instruction.
Role of Women in Society
Women were not allowed in the army. This is something that Mulan does not agree with nor appreciate especially considering that she is a skilled martial artist and strategist who wants to do her duty. This shows that the role of women in society was to wait at home for the men to return rather than participating in the fighting itself. It also shows that women's roles were considered to be more dutiful in the home; they ware not expected or allowed to do much work outside it.
Country Over Self
This being a sanctioned Chinese movie, the theme of country before self is predominant throughout, because this is a message that the Chinese government can definitely get behind. At various stages of the film, characters remind each other about their "duty", which is generally putting themselves at risk for the good of the country. At the end of the film when Mulan is in love, she gives up that love so that her beloved can marry a princess and bring long term peace to the nation; Mulan sacrifices her own true love and happiness for the good of the country's future.