Nickelodeon All-Star Brawl does not feature characters from live-action Nickelodeon series. According to Ludosity CEO Joel Nyström, this was due to the developers being unable to envision movesets for live-action characters (i.e. "I'd assume they don't feature a giant, two-ton hammer suddenly produced from your back pocket") and that many of the series did not air in Sweden. When asked about live-action content in an interview, he stated


Despite this, a developer from Ludosity has claimed that a live-action character was considered in the form of Alex Mack from The Secret World of Alex Mack, portrayed by Larisa Oleynik, but this was shot down by Nickelodeon.

Although not explicitly stated, it could also be assumed that live-action characters were off the table for likeness costs, given that All-Star Brawl was initially unable to afford character voices, and that actors involved in Nickelodeon sitcoms have been known to frequently get into extreme scandals that end their careers.

Nickelodeon All-Star Brawl does, however, feature a stage based on the game show Double Dare, and multiple aesthetic references to the iconic Nickelodeon slime which debuted in You Can't Do That on Television!

Alongside Garfield, Rocksteady from Teenage Mutant Ninja Turtles was originally going to be one of the two post-launch playable fighters in Nickelodeon All-Star Brawl - notably without his partner-in-crime Bebop, much like Michelangelo and Leonardo's inclusion without Raphael and Donatello. He was ultimately replaced by Shredder, and all that remained of his inclusion at launch was a placeholder stock image and the codename "hunter".

Rocksteady would eventually become playable in Nickelodeon All-Star Brawl 2.

Competitive players of Nickelodeon All-Star Brawl nickname Rocko's grounded neutral strong attack, "Scream!", "Joe Biden" after a mondegreen interpreting Rocko's scream of "You're fired!" (a reference to the episode Power Trip, where he gets promoted to the boss of the comic book shop he works at and becomes mad with power) as "Joe Biden!"

NASB community manager Thaddeus Crews responded to a now-deleted tweet about the mondegreen with "canon", and later posted a stock render of Rocko with the caption "Joe Biden".

While most other characters in Nickelodeon All-Star Brawl 2 recieved revamped movesets, Jenny's moveset is nigh identical to her moveset from the first NASB aside from inputs that didn't exist in the NASB 1 moveset template. This is due to moveset and gameplay designer Thaddeus Crews considering Jenny's moveset to be one of his favorite kits from the first game.

One of Ren's voice lines on Nickelodeon All-Star Brawl, used for his and Stimpy's grounded down strong attack where he slams down Stimpy as if he were a hammer, is a reference to the streamer CONEY, who in his post-launch NASB gameplay referred to the move as "the STEEEEEEEEEEEMPY", with Ren's second original series voice actor Billy West replicating the cadence of CONEY's scream.

There exists an unused model in Nickelodeon All-Star Brawl of Patrick's head after being shoved through a trombone, in reference to the SpongeBob episode Band Geeks.

If you pause the game on Jellyfish Fields, Gary's eyes will start to bizarrely drift away from one another. When you unpause, they snap back in place.

When used on the Wild Waterfall stage, the Suck-O-Matic can suck up the log platforms, altering the layout of the stage.

Nickelodeon All-Star Brawl's movesets are modified through mathematical functions. Due to the monotony of assigning these values, certain modifiers' values are set to be pi solely as a joke. Thaddeus Crews, who added the instances of pi, stated in a Reddit post about the use of the number:

During development of Nickelodeon All-Star Brawl, Patrick's gravity accidentally ended up being set to 420 in certain unspecified circumstances. Thaddeus Crews stated that it was kept that way as a joke.