I played in a LAN world with my brother and I saw a pig with my brothers texture. then I found out that my brother's player skin is white.
some of the entitys like: boat and items, gets white too.
mobs lose their texture too: pigs, cows, skeletons, spiders, zombies.
another thing I saw is: when I swam in the water, they had the wood texture.

(I used other texture pack before, not 13w18a texture, im not sure if its related...)
the wierd thing in the pictures is enderchest-pig