- Development Hell: Daikaiju Daikessen: Versus was intended to technically the second game in the fanchise. The first — simply titled Daikaiju Daikessen and originally "The War of Monsters: Daikaiju" — is a demo featuring Super-Deformed kaiju characters only available on Itch.io; and it has gone through numerous iterations since 2014. A Game-Breaking Bug surfaced in July 2021 that forced the fighting game version to be scrapped and reworked into a roguelike game called Daikaiju Daikessen: Rogue.
- Exiled from Continuity: The MonsterVerse versions of Godzilla (from Godzilla: King of the Monsters) and Kong (from Kong: Skull Island), Shin Godzilla, and the Heisei incarnation of Gamera were added as unlicensed guest characters while the game was only available on Itch.io, but were removed when it was added to Steam to circumvent getting Screwed by the Lawyers.
- Fan Nickname: Ascha'Vovina has gained the nickname "XenoZilla" — a portmanteau of "Xenomorph Godzilla" — due to the character's Gigeresque appearance.
- Official Fan-Submitted Content: Most of the monsters are OCs submitted by various members of the Kaiju fandom.
- Ascha'Vovina (as Asura), Cymothia, Gaonaga, Giga Raptor, Gurral (who is also the protagonist of an indie webcomic titled Gurral the Smasher), and Hyenia (as the Hound of Nita) were originally created for and/or submitted to Colossal Kaiju Combat! before it went belly-up.
- Atomic Rex is the protagonist of a series of kaiju novels.
- Draco Azul is the protagonist of the indie comic Primal Warrior Draco Azul.
- Durontus is the kaiju protagonist of the The Lost Serpent and Durontus: Attacks! comics.
- Irokus was created by Frank Parr for the Irokus: Mirror Image novel.
- Evil Ujiak is the mascot of the Kaiju Live podcast.
- Titanicus is the mascot of Titanic Creations.
- Yirmatang and Yumiko were created for a short story submitted to G-Fan Magazine Issue #119.
- What Could Have Been:
- Daikaiju Daikessen went through a series of developmental iterations before VERSUS was released as a beat-em-up in the style of King of the Monsters and Godzilla: Domination, including an RPG focusing on the human characters, a side-scrolling platformer, and a more traditional 2D fighting game in the vein of Godzilla: Monster War. Several of these ideas wound up been reworked into the spinoff Daikaiju Daikessen: Operation Guardian.
- Daikaiju Daikessen: Versus was originally going to have a story mode, but this is being reworked into the spinoff title Daikaiju Daikessen: Operation Guardian.
- Update 1.9 is set to merge the Survival and Versus modes together, as well as remove the game's currency and store for unlocking kaiju.
- In 2021, a Game-Breaking Bug was encountered when the game grew too big for the engine to handle, leading to the Versus project reworked and streamlined into the Roguelike-style single-player beat-em-up Daikaiju Daikessen: Rogue.
aka: Daikaiju Daikessen Versus