Call Back: The Bonus Dungeon Via Infinito can roughly translate to 'Endless Road'. Now, what was the name of Tidus' best armour last time again? Yes, Endless Road (Break HP and MP Limit).
No Export for You: X-2 International+ Last Mission, which is pretty maddening considering it has a complete additional game where it addressed many of the complaints by fans on Yuna and Rikku's change in personality.
Subverted, as they eventually released Final Fantasy X / X-2 HD RemasterPlayStation 3 and PlayStation Vita, which contains International content and Last Mission.
Non-Singing Voice: Jade Villalon sings for Lenne in the English version, while Cree Summer is the speaking voice. Not that Summer's unable to sing; she's released an album. Villalon technically sings whenever Yuna does in the cutscenes (as Yuna's implied to be singing with Lenne's voice). However in the battles, Hedy Burress sings whenever Yuna does (if she's a Songstress that is). Ditto for Tara Strong and Gwendoline Yeo whenever Rikku and Paine sing in battle. In the original Japanese, Lenne's speaking and singing were both done by Koda Kumi.
Type Casting: Rikku's English voice in the previous game was slightly different for Tara Strong, due to the trauma muting some of her optimism. However here she's a full on Genki Girl, making this within type for Strong.