According to the game's producer Xavier Manzanares, the decision to have nine playable heroes was made so that each character would fit an archetype in terms of strategy and tactics in battle. This choice was made even before they knew what the game's roster of heroes was going to be.

The game's title theme sounds similar to the Space Junk Galaxy theme from Super Mario Galaxy.

The idea of the Sparks came about as a way to evolve the combat system from Mario + Rabbids Kingdom Battle by stepping away from its focus on traditional weapons and the option to discard weaker weapons for better ones. However, the developers felt that the Sparks needed to visually fit into the game's world and not just function as "skills", resulting in a lengthy design process. According to lead producer Xavier Manzanares, the design of the Sparks as seen in the game's promotional art was the 25th attempt at designing them.