Nice find. I fought that battle dozens of times and didn't pick up on that.
The Nosdu Mountain Range is a giant mana crystal mine, so it kind of makes sense that Iris would beef up her "Iris Machine" with a Magus's equivalent of steroids. It just goes to show how much Iris intended to totally slaughter Tia in their first real battle (and explains how she'd have enough mana to fire off that many spells in rapid succession).
As a side note, raw mana crystals are red stones, whereas refined, readily-usable crystals are blue spheres. Why is that? Couldn't tell you...
Anyway, the full title of the stage is "Mining for Mana Crystals in the Mountains of Nosdu". I couldn't fit it all onscreen, so I had to make a compromise somewhere. "Mana Crystals" could have been a reference to Magirock in Terranigma, but I thought the term was generic enough that it might just be a coincidence. A Phoenix Down isn't automatically a Final Fantasy reference, for instance.