Mint, the White Magician Girl in Tales of Phantasia, is the angel that revives your characters when you cast Resurrection. The background during the spell also show a close-up of her opening her eyes, straight from the animation of Phantasia's opening theme.
In the same sense, Arche the Squishy Wizard shows up in one of the spell animations to blast your enemies with meteors. There's also a way to temporarily turn either one of your mages into her Unexpected SHMUP Level incarnation from PS1 version of Tales of Phantasia, allowing them to fly around the screen and shoot the enemies with spells.
You can get Stahn's trademark Deck Brush if you poke around your Cool Ship.
Speaking of non-Tales Of related cameos, an optional dungeon (which contains an essential part of the Global Airship ) sports Rick Taylor from Splatterhouse, the undead samurai from Genpei Toma Den and spirit world statues from Shadowland, not to mention that one of the Bonus Bosses is the Valkyrie from The Legend of Valkyrie (her dungeon even has the same music from the first level of that game).
The equipment shop in Barole has a genuine suit of Cless's armor, cape and all, hanging on the side. It's easy to miss.
The Water Craymel Lab has a shoutout to Phantasia that you can find once you get Keele in your party.
"If evil exists in the world, Craymels are at the heart of mankind."
One of the collectibles in this game are lens. Yes, those lens. You can show your lens to one Ilene Rembrandt for various rewards. Getting all 60 gives you the "Lens Hunter" title. "Lens Hunter" was Rutee's self-proclaimed job in the last game.