This is what a white Pegasus looks like, all pegasus' have white wings, unless you are using the V2 Graphics
Unicowrn
These are EXTREMLY rare. the only way to get them is to buy them, they are SUPER EXPENSIVE, or to breed them at exactly 6:23 game time, then you only have like a 1/6 chance the foal will be a unicowrn.
A golden apple coat
There are hundreds of Golden apple coats, this is just one. A golden Apple coat is made with the Black Pearl, you can also buy a golden apple with a pass, this lets you change your horses coat to one of these special ones.