On my custom texture pack, donkey & mule ears are missing, spiders' and endermen's eyes doesn't glow, firework star's overlay texture is missing. This happens despite checking files again and again only to find that they are absolutely correct. I downloaded another texture pack and it had just a few of these problems. But yet another texture pack I downloaded had all of them, so that means those bugs aren't consistent, maybe it's because of minecraft version they were created in? I tried to compare their differences but found absolutely nothing. Mule and Donkey's ears happened in 1.6.0 but other problems I mentioned existed in versions prior to that such as 1.5.x