The retail version of the Avatar of Flame (Runebound Firelord) holds a fireball in his hands while using the /mountspecial animation.
The WotLK version is missing the fireball from his hands.
Retail version: https://i.imgur.com/LLzzKCm.png
WotLK version: https://i.imgur.com/oWFuXJK.png
Also the idle animation of the WotLK version is extremely bugged. The character hovers above the mount instead of standing on it. (Someone already made a bugreport about that.)