The wording of Wild Arcana (errata notwithstanding) states
As a swift action, you can expend one use of mythic power to cast any one arcane spell without expending a prepared spell or spell slot. The spell must be on one of your arcane class spell lists and must be of a level that you can cast with that arcane spellcasting class.
You don't need to have the spell prepared, nor does it need to be on your list of spells known. When casting a spell in this way, you treat your caster level as 2 levels higher for the purpose of any effect dependent on level. You can apply any metamagic feats you know to this spell, but its total adjusted level can't be greater than that of the highest-level arcane spell you can cast from that spellcasting class.
Does this mean that since the spell doesn't "need to be on your list of spells known", you could in theory cast any mythic version of a spell at the cost of two mythic points (one for wild arcana and one for the mythic version)?