Shinobu's outfit in No More Heroes is based off the Japanese "kogal" style.

In the cutscene before the fight with Harvey Moiseiwitsch Volodarskii, the subtitles misspell Volodarskii as "Volodarsky".

Death Metal's saber, the Orange II, was designed by the fictitious "Orange Computers", a parody of Apple Inc.

The assassin Dark Star resembles the Darkstar Skateboard Logo.

Travis' bike "Schpeltiger" resembles Kaneda's motorcycle from "Akira."

The suggestive motion that Travis (and the player) must perform to recharge the Beam Katana resembles a masturbatory act because the japanese word, "自家発電", means both "Manual power generation" and "masturbation".

The mini-fridge in Travis' room at Motel "NO MORE HEROES" can be used to heal him, even though it's impossible to lose health outside of ranking matches and assassination gigs and Travis' health is always restored after completing or failing a gig. Both the game and its instruction manual still point out this feature regardless. This suggests that there were either plans for enemies to appear in the overworld of Santa Destroy that could harm Travis outside of his missions, or it was implemented purely for creative effect.

In the original Wii version, the river overpass in Santa Destroy has a wall underneath it with poor-enough collision detection that if you walk into it in a certain way, Travis will clip through the wall and can walk infinitely directly underneath Santa Destroy, even out of the city. This glitch was fixed in all future re-releases of the game.