A secret message can be found on the title screen of the NES version of the game with the use of two controllers. At the title screen, select "CONSTRUCTION" on the menu. Press Start on Controller 1 to enter the mode, then press it again to return back to the title screen. Repeat this seven times. After the seventh enter-and-exit, hold Down on Controller 1 and press A eight times on Controller 2. Then, hold Right on Controller 1 and press B twelve times on Controller 2. Finally, press Start on Controller 1 to activate the message featuring an animation of a green droplet falling:


The most likely person as to the identity of "Open-Reach" is Tomcat System's founder and programmer Ryoichi Ookubo because of the similarities between "Reach" and "Ryoichi". It should be also noted that his name is hidden twice in the game's ROM, and from one fact pointed out by a Russian LiveJournal user, that the name Open-Reach appears as "OPR" on the title screen of another game Tomcat System developed, the 1991 Famicom game Castle Quest published by Hudson Soft.

As for Noriko, her identity remains unknown. In the comments section of the sourced video, one commenter claimed that Noriko was Ookubo's daughter who was three years old at the time of the game's development, while the aforementioned LiveJournal user claimed that Noriko was a romantic partner, claiming her to be a former Namco graphic designer named Noriko Ikegawa (whose name would later appear in the credits for the Nintendo game Animal Crossing as a model designer), but there is no known substantial evidence to support either of these claims.

An unused pistol powerup can be found amongst the NES version's sprite data. This powerup would have made the player invulnerable to three enemy shots like the heavy tank powerup, but was replaced by the helmet in the final game. Interestingly, it shows up in a pirated version of the game called Tank 1990.

Star Fox: Assault is notable for including three unlockable Famicom/NES games originally created by Namco:

• Xevious
• Battle City
• Star Luster

As explained by the development team in an issue of Nintendo Dream, this was done to highlight Star Fox: Assault being a collaboration between Nintendo and Namco, with the latter being its primary developer. With the Star Fox franchise being a sci-fi shooter series, Tsuyoshi Kobayashi and Takaya Imamura had carefully decided on which classic Namco games would fit the best with that vibe. There were considerations to also include Nintendo created Famicom/NES games (one person, for example, had suggested including Balloon Fight), but ultimately Imamura and Kobayashi couldn't come up with any games that would have fit the Star Fox world and atmosphere.

Unfortunately, as the Famicom versions of Battle City and Star Luster had never been released in Western territories, they in turn were excluded from all Western versions of Star Fox: Assault, leaving Xevious as the only unlockable Namco game outside of Japan.