Within the game, there exists a model of a generic Hero class found in the training grounds in the later half of the game, and class data for an unused Hero class exists within the game that can be loaded in.

It uses the generic attacks of the 'Mercenary' Class but lacks the animations for it's class action despite having 2 meters for it, suggesting that it was meant to be a promotion for the class rather than Swordmaster being the sole promotion to Mercenary.

War Monk, Dark Flier, and Valkyrie also exist within the game's code, but they're in an extremely unfinished state as they lack a Sprite, Model, Text, and any functional abilities. They do however have Class Stat bonuses assigned to them, hinting that at one point they were considered to be brought back.

Despite being playable in Fire Emblem: Three Houses, Gilbert, Anna, Cyril, Hanneman, and Alois all have recruitment flags (the internal value which tells the game if the unit is in your army or not). They lack any skills or data assigned to them however and trying to deploy these units or use them in battle with crash the game.

Interestingly, Gibert is not referred to by his real name nor is he sorted to be with Kingdom characters despite his role in the Three Hopes story. However Alois is always sorted to be next to Jeralt and Byleth in the menu, rather than with the Church like in Three Houses.

An unused battle model of Edelgard's Hegemon Husk exists within the data of Three Hopes, as seen with the head that now matches her Three Hopes design it is an original model made for this game.

As the cutscenes in the game are all pre-rendered, and that is the only time we see Hegemon Edelgard in Three Hopes, it is speculated that the seen where she transforms may originally have been a boss fight.