Extract from an interview with the Firefly cast at Zeta Minor :
Q: What kind of training did you do for Serenity?
Morena Baccarin: I was in a ‘fight club’ for three weeks. I was trying to do one kick for probably two weeks.
Nathan Fillion: I was there barely three weeks. And I would complain about my time there, and every time I’d come in there I’d see Summer (Glau) doing her thing, kicking something above her head about 60 times. I’d be warming up and doing my stuff, cool down and leave, and she’s in the corner fighting nine guys. And she had to start months before us. She worked really hard.
Excerpts from this interviews have been reproduced in the Firefly 10th Anniversary book.