According to the game's director, John Johanas, Chai's hospital gown from Track 1 was meant to be an unlockable costume. However, the physics of the costume didn't respond well to Chai's moves and thus got scrapped.

The January 2024 update celebrating Hi-Fi Rush's one year anniversary includes new t-shirts that players can wear in-game. Some of these t-shirts are exclusive to their own platform (Xbox, Steam, and Epic Game Store):

• Xbox owners get a green shirt saying “shadow dropped”, a reference to the game’s surprise release.
• Epic Games Store owners get a shirt saying “this is simply unreal epic”, obviously a reference to Epic Games and the Unreal engine and series.
• Steam owners get a shirt saying “Be Positive (Overwhelmingly)”, an obvious reference to Steam’s user review system.

However, two more additional exclusive shirts have recently been discovered through datamining that seem to curiously pertain to the Nintendo Switch and PlayStation 5, two competitor platforms to Xbox.

• The red shirt seemingly for Switch says "rock out anywhere", obviously referencing the Switch's portable nature.
• The blue shirt seemingly for PS5 says "I'm here baby", possibly a reference to the game finally arriving on PS5 after a year of being exclusive to Xbox platforms.

In early 2024, Hi-Fi Rush was the subject of various rumors claiming that Microsoft planned on porting it and possibly other first party Xbox titles to its competitor platforms, those specifically being PlayStation 5 and Nintendo Switch. In response to these rumors, Microsoft Gaming CEO Phil Spencer announced in an Xbox Business Update on February 16, 2024 that four of their previously Xbox exclusive titles were being brought over to rival platforms. On February 21, 2024, it was announced that Hi-Fi Rush, along with Rare's Sea of Thieves and Obsidian's Grounded and Pentiment, were all being released on PlayStation 5 (and Nintendo Switch as well as PlayStation 4 for the latter two games), fully confirming the rumors.