OS: Windows 7 Home Premium
Java: Version 7 Update 45 (build 1.7.0_45-b18)
Launcher: Minecraft Launcher 1.3.7 (bootstrap 5)
In the attachment, there are 5 pink sheep, a burning zombie and waldo hidden in this picture. The problem here is that there are 5 pink sheep. As posted in the Minecraft Wiki, pink sheep have a spawn rate of 0.164%. The odds of 5 spawning in one place are near zero. Whats more, in this Savanna biome, there are more than 20 pink sheep total (Along with about 60 White sheep).
To view this for yourself,
use version 1.7.4,
(Default world, no large biomes)
The coordinates of the sheep are 601 82 -547. Just fly around and you will see them all.
Perhaps this is a glitch just included in this world, or maybe it is because a pink sheep spawned in a Savanna biome... It would be very difficult finding another pink sheep spawn in another Savanna biome on a different world, so maybe we will have to just wait to see.