Elena's Undergarments from the Mask of Zorro include four pieces: a corset, a chemise, pantaloons, and a blue semi-sheer robe. Don't forget to check out Olivia's MOZ Research site Threads of Elena for more information on this costume.

Corset - Elena's corset is a one piece nearly-underbust corset with hip gores and a front closure. From pictures I've been able to find and by watching the movie, I'm still not certain how the corset closes in front. Most likely it's with a metal busk, but it's hidden very well. Possibly it closes with hooks and eyes, or lacing, but I don't know for certain either way. It's made from a patterned white on white fabric and most likely is interlined with coutil and reinforced with steel boning in all of the seams. The edges are bound with the same white fabric. I believe the corset laces in the back but I'll need to watch the movie again to be certain.

Chemise - Under the corset, Elena wears a knee-length chemise. It has a low scoop neckline and small slightly poof-ed cap sleeves. The neckline is embellished with small lace that is threaded with blue ribbon to pull it closed. The sleeves also have lacing at the hem (you can see where it's been tied off to create a bow in picture #1), I believe to gather them into the correct fullness.

Pantaloons - Under the chemise and corset, Elena wears a pair of white pantaloons (though these are not visible when Zorro slits the thigh on her chemise). There is a drawstring waistband that ties closed with a blue ribbon and the pantaloons end about to the knee. The pantaloons are worn very low on the hips and fit loosely to the body. If they are period accurate, it's most likely that the pantaloons are split at the crotch to allow for certain... necessities. I believe the bottom hem of each leg is embellished with lace, but couldn't say for certain.

Robe - Elena's robe is made from a semi-sheer fabric (silk?) and ties with a matching blue rope cord that acts as a belt. There is a shawl collar of shiny satin and this satin is repeated on the 3/4 sleeve cuffs (about 3" deep). The robe is approximately ankle-length.

Linkage:
Threads of Elena - Olivia's Zorro research site