Inside a GIF file, a palette can be redefined anywhere, and in between chunks of image data. Using that trick, you can pull 24-bit colour GIFs. There are two problems about it: most GIF editors don't use this trick, and it makes the GIFs grow significantly (50 MB GIF anyone?).

Raher than pushing an old technology, I'm surprised they didn't go for a better, modern alternative, like WebM.