SpongeBob becomes offended when Clockwork refers to him as "SpongeBoy." SpongeBoy was the character's original name in the initial pitch for the show, then called "SpongeBoy, Ahoy!" This was later changed due to the original name already being copyrighted.
When El Tigre is chosen on the select screen, there is a random chance the announcer will call out his real name instead: Manuel Pablo Gutierrez O'Brian Equihua Rivera.
Azula is the only character who does not wear their default costume in the cover art. The artwork uses her outfit from Book Two of Avatar: The Last Airbender (2005), whereas her default outfit is from Book Three.
For Patrick's Super attack, characters were originally going to have unique "crushed" designs/animations as they were hit, as announced via Twitter. SpongeBob's was revealed during Patrick's character showcase, where he was transformed into a yellow splat. The feature was quietly removed before the game's official release.
In unique dialogue with Ember, Vlad says she is still a scared little girl begging for attention. This is a reference to her backstory, as confirmed by one of the directors of Danny Phantom (2003). When she was alive, Ember was an unpopular girl who dreamed of being a famous musician. A jock invited her on a date to the movies, but stood her up, leaving her waiting in the snow for hours. Ember returned home exhausted and did not wake up when her house mysteriously caught fire. Clockwork also references this, stating he has seen Ember's past and future, and that she is not all bad.