Spyro: A Hero's Tail was developed by the same team at Eurocom that made the Xbox, Nintendo GameCube, and Game Boy Advance versions of Harry Potter and the Chamber of Secrets. During development, the team created internal test maps so multiple programmers could work on level assets and gameplay mechanics at the same time. Once their work was finished, the completed content would be transferred into the main stage. Although these testing maps were never intended to ship with the final game, they remain on the disc and can be accessed through cheat codes or file-swapping. The game disc also contains two additional unused maps, hogwarts.edb (a model based on the famous Harry Potter location) and maptest.edb. According to co-producer Jon Williams, he could not recall their exact purpose, but believed they were likely used to prototype ideas before Eurocom transitioned to its EngineX technology. Another leftover development feature, Scanmode Enable, appears in the debug menu and disables collision detection, allowing developers to freely move through and inspect entire levels.

Spyro: Enter the Dragonfly's villain was originally going to be a dragon, but the lead designer was adamant that the Spyro universe could not have any evil dragons. Ironically, the following release Spyro: A Hero's Tail would introduce Red, an evil dragon.

In the prototype version of the game, Blink's hat is red as opposed to purple in the final.

Hogwarts can be found hidden in the game files. EuroCom also developed a Harry Potter game, so it was likely imported to test Sgt. Byrd's flight mechanics.

Mrs. Shoutfire's name is a reference to the character Mrs. Doubtfire from the film of the same name.

Utilizing a glitch that allows the player to swim in mid-air, while in Coastal Remains it is possible to see an unfinished building floating in mid-air.

The Dragon Elders Tomas, Magnus, Titan and Astor are all based on characters from the first Spyro game. However, their appearances have been dramatically altered.

There are several references to the Mario franchise througout the game:

• When attempting to activate the ball gadget, The Professor mentions two signature items in the Super Mario series, Power Stars and Red Coins, when trying to recall the name of a valued collectible, the Light Gems. Not only this, but he mentions Heart Pieces as well, which is a reference to a collectible found in The Legend of Zelda series.

• There is a robot NPC named Mergatroid found in Red's Laboratory who wears a red shirt, blue overalls, and a red cap with the letter "M" on it.

• There is an enemy type in Crocovile Swamp that resembles a Piranha Plant. A variation of this enemy also spits fireballs, much like a Venus Fire Trap.

• Lastly, there are hostile Yetis in Gloomy Glacier who throw barrels, similar to Donkey Kong.