So often I feel that Lucy got the short end of the stick in the costume department because her outfits are not very exciting. One thing I know for sure is that Susan has an amazing wardrobe and this dress and her farewell dress are my favorites. They are similar in many ways, both having off the shoulder necklines, and overdress and underdress with the sleeves as being the most complex part of the outfit. I read up on the outfit and it appears that the pink sleeves are attached to the green dress and from my knowledge of sewing I would assume that the green part that peeks through the slits in the sleeves is probably a fake undersleeve. The practice of having slits in dresses and having "undergarments" peeking out is common with Narnian clothing, and I did a study on one of the other Narnia dresses and how it was constructed and concluded that while possible that it was possible it was actually an undersleeve, it was unlikely due to practical purposes. If you look at how smooth the pink sleeves are laying and then how puffed the green parts are, I find it hard to imagine that there is actually a complete additional sleeve under that. Anyway, I find it interesting that they make it appear to be so many different layers in all of the Narnian clothing.
Random thing I noticed: Last time we see the Pevensies in Narnia, Lucy is wearing red and orange and Susan is wearing purple. First time we see them in Narnian garb in Prince Caspian, Lucy is wearing red/orange and Susan is wearing purple. I wonder if that was done intentionally