I didn't know that. I thought I remembered reading somewhere that the Ra's was wrong, and that Christopher Nolan knew that and didn't care. Pretty much everything I've seen with the character other than this and Nolan movies pronounced it Raysh.
Like stated, neither is technically correct but there seems to be a constant disparity between animation and live action.
The DCAU and films pronounced it as Raysh, while Nolan's movies and now Arrow pronounce it as Razz.