- According to a leak that was found while digging through game files before his release, Uno's name was originally Kueltuel.
- According to the same leak, Uno would have used the weapons Excalibur and Katana.
- While Katana was most likely renamed to Blood Dancer, Excalibur never made it into the game.
- Uno does not have an official surname, similarly to Rin.
- Reina, from Uno's history, may be a play on the Elsword character Rena.
- Uno is considered a "pure" MP character. He does not have a skill tree.
- Uno is the second male character with Type 2 Abilities for all 3 skill levels. The first is Lass.
- At the center of Uno's emblem is The Ouroborus, the Eternal Serpent. This is most likely symbolic to how Uno's body forever uses his own blood as a source, forcing to take the blood of others.