20 Things You Didn't Know About Serenity
10. The Costumes Were Left Over By The Postman
If any of the costumes in Serenity look familiar, they might be.
The actors in the docking station scene actually wear the "Army of 8" uniforms from the 1997 post-apocalyptic film The Postman (directed by Kevin Costner) that were left-over on the set.
Another quick fact for you - some costumes from Firefly were borrowed from another 1997 sci-fi movie: Starship Troopers.