PaRappa's intro and ending were made by the same company who did the PaRappa the Rapper anime.

Nariko, Sir Daniel and Jak are the only characters who's original voice actor did not reprise their roles in this game (though Jak and Nariko have their original voice actors in the Italian version).

Cole MacGrath, Emmett Graves, and Kratos are the only characters that have an alternate costume based on a different character. Cole's being Kessler, Kratos being Deimos, and Emmett Graves being Logan Graves.

The boss "Polygon Man" was actually the Playstation's original mascot from 1995. He was meant to demonstrate the power of the Playstation, but was dropped shortly after the Playstation was announced.

The developers of PlayStation All-Stars Battle Royale expressed that they wanted Mario as a playable character in the game as a nod to the Super Smash Bros. series.

A prototype build for PlayStation All-Stars Battle Royale shows an early character select screen with a set of unused characters:

• Chop Chop Master Onion from the PaRappa the Rapper series
• Captain Blasto from Blasto
• Buzz from the Buzz! series
• A Big Kulche from the LocoRoco series
• Dr. Nefarious from the Ratchet & Clank series
• A Eucadian Soldier from Warhawk
• A knight from Fat Princess
• Um Jammer Lammy from the PaRappa the Rapper series

Notably, Dr. Nefarious is featured in the roster without Ratchet or Clank. PaRappa the Rapper is the most represented series in this roster, and has more characters than any one series would get in the final game including DLC. The knight would appear in Fat Princess' moveset, LocoRoco and Buzz! would be represented through stages, and Blasto would be absent completely.