Not sure if you guys are aware of this issue already.

Some currencies are showing missed itens or mounts that are exclusive to teh other faction. Saw this on Argent Tornament and in Nazjatar. Will post some pictures for you guys to check it out.

I Belive I've already bought all there is to buy with my Prismatic Manapearls. But when checking the tooltip of the currency, it shows that i'm missing a mount. That is exclusively Horde. I'm Aliance at the moment.

This mount is not exclusively Horde though, if you unlock it on Horde, you can mount it on Alliance characters. But you are right in a way that you can't unlock it on Alliance, I agree with you. I asked about it before and as far as I know right now there is no way to filter out stuff for other factions from currency list unfortunately. Unless someone somehow implements this functionality this stuff will show up.