While me and a friend were playing Minecraft together, I saw the my friend's character with a arm detached,  when their character moved, the legs weren't moving like normal, and when it finally became night, her character was standing while sleeping, which normally doesn't happen.  I fixed it, but for a little while.  This is confusing, overall, it didn't happen the last time she was here.  Can anyone on the Mojang team figure out why this is happening?