For trivia pertaining to this monster's Number, see Forum:"Numbers" Xyz Monster Trivia. Any contributions regarding this type of trivia should be placed there, instead of this page.
- This monster is the signature card of both Yuma Tsukumo and Astral.
- As an Xyz Monster, it is the first signature card of a main protagonist to not possess a Level.
- It is also the first Xyz Monster Yuma summoned in the anime.
- This card is also used in the ZEXAL manga by Yuma Tsukumo and Astral, but has a different Xyz Evolution method (Chaos in the anime and Shining in the manga).
- This card has the same ATK of 2500 as the signature cards of other main protagonists, both in anime and manga.
- When this monster uses its effect to negate an attack, its wings form a shield that blocks the attack. When this monster negates its own attack, its swords disappear.
- This card's Japanese effect name, "ムーン・バリア" (Moon Barrier), is a joke based on the fact that the "望" character of "希望皇" (King of Wishes) in this card's name can be read as "full moon".
- This monster may have originally been intended to be Number 3 as shown in Duel Art.
- This card is one of the first three Xyz Monsters to be released. The second is "Gachi Gachi Gantetsu" and the third is "Grenosaurus".
- This card is the first card to be the Cover Card of two different Starter Decks: Starter Deck: Dawn of the Xyz and Starter Deck: Xyz Symphony.
- In Starter Deck: Xyz Symphony, this card's Set Number is YS12-EN039, which is the same as its number.
- This is the first Xyz Monster to be released as Gold Rare in the TCG, in Gold Series: Haunted Mine.
- Yuma's signature card is similar to Yusei's "Stardust Dragon" in that both monsters have a protective negate effect and the most evolutions and counterparts of their archetype (specifically, "Signer Dragons" and "Numbers").
- Alternate "Number" forms
- Evolved "Number 39" forms via Xyz Evolution
- "Number 39: Utopia Beyond" (a Rank-Up form with "Rank-Up-Magic Astral Force")
- "Number 39: Utopia Roots" (a Rank-Down form with "Rank-Down-Magic Numeron Fall")
- "Number C" forms via Chaos Xyz Evolution
- "Number C39: Utopia Ray" (without a "Rank-Up-Magic" card)
- "Number C39: Utopia Ray V" (with "Rank-Up-Magic Limited Barian's Force")
- "Number C39: Utopia Ray Victory" (with "Rank-Up-Magic Numeron Force")
- This card is the only evolved "Number" to have more than 1 "Number C" form.
- "Number S" forms via Shining Xyz Evolution
- "Number S39: Utopia Prime" (without a "Rank-Up-Magic" card)
- "Number S39: Utopia the Lightning" (with "Rank-Up-Magic Shining Force")
- This card is the only evolved "Number" to have any "Number S" forms.
- This monster appears in the artworks of: Token (Astral and Number 39: Utopia), Bonds of Hope, Final Countup, Generation Force, Grave Chaos, Hope 1, Light Wing Bumper, Light Wing Shield, Number Return, Number Spell Caster, Numbers Evocation, Numbers Impact, Overlay Reborn, Overlay Rebirth, Purge Ray, Reservation Reward, Rising Sun Slash, Superior Overlay, Tsukumo Slash, Ultimate Xyz, Utopia Buster, Utopia Rising, Utopian Aura, Utopian Hope, Weaker Overlay, Xyz Energy, Xyz Reborn Plus, Xyz Revenge Shuffle, Xyz Shift, Yu-Gi-Oh! ZEXAL and Zexal Entrust.
- This card appears in the artworks of "E☆HERO Pit Boss" and "Numeron Xyz Revision".
- This monster's sealed form appears in the artworks of "Double-Rank-Up-Magic Utopia Force", "Rank-Up-Magic Dark Force", "Xyz Change Tactics" and "Xyz Treasure Ticket".
- This card's English name, "Utopia", is a literary term used for a perfect society or community. The word originated with Sir Thomas More, in his 1516 novel of the same name.
- In fact, in his book, he wrote a small segment describing the games played by the Utopians (people of Utopia), which together loosely describe the battle of "Numbers" in the ZEXAL anime: "They have, however, two games not unlike our chess. The one, a battle of numbers, in which number consumes number. The other, a contest between the virtues and vices, in which the discord among the vices themselves and their union against virtue is not unpleasantly represented."
- This card's Japanese name could be an allusion to the myth of Pandora, a woman who opened a box that unleashed all sins upon the world. In the myth, the only thing to remain in the box was hope. Similarly, "No.39" was the only Number to remain in Astral's possession, after Yuma unleashed the Numbers.
- "Numbers" take the form of their original owner's desires. In this case, it is to remain strong, never give up, and protect.
- This monster appears to be the most loyal "Number" to Astral. In episode 37, when Number 96 attacked Astral, this monster protected him. Also, it acted completely on its own as both Astral and Number 96 were clearly surprised, implying that this monster, like "Number 83: Galaxy Queen" and "Dark Mist", has a mind of its own.
- Utilizing the effects of "Number 100: Numeron Dragon" and "Number 73: Abyss Splash" via the effect "Utopia Rising", as well as "Double or Nothing" to double its ATK further, this card reached 204,000 ATK, the highest finite attack value attained in the anime.
- This is the first card whose Korean name (No.39 유토피아 "No.39 Utopia") follows both of TCG and Japanese schemes.