- Distanced from Current Events: After 9/11 the NSA agents stopped making references to terrorism or Zeta being mistaken for one. ...which is Hilarious in Hindsight as, after 9/11, the NSA became more focused on terrorism in Real Life than they ever had been back when the series started, although they were fighting domestic terrorism when the show was first written.
- Executive Meddling:
- The Other Darrin:
- Both Zeta and Agent Bennett. They were voiced by Gary Cole and Joe Spano respectively in their debut on Batman Beyond, but The Zeta Project and their subsequent appearances on Batman Beyond had them voiced by, again respectively, Diedrich Bader and Kurtwood Smith.
- In "Absolute Zero" Dr. Selig was voiced by George Segal; for his second (and final) appearance in "The Hologram Man" Hal Linden voiced him.
- Talking to Himself: Diedrich Bader voices both Zeta and IU7, though he is only credited for the former.
- Theme Naming: Zeta and Ro (well, "Rho") are both Greek letters.
- What Could Have Been:
- The show was actually envisioned as being darker than Batman Beyond, but Kids WB wanted it to be more marketable towards children.
- Along with the darker tone, Zeta was originally going to continue struggling to not kill, but his killer streak would still sneak through from time to time.
- Ro was originally raven-haired.
- The third season, which would resolved the Cliffhanger ending in addition to Zeta eventually finding Dr. Selig.
- Jon Schnieder planned to create a live-action reboot, where Ro was an FBI cyber crimes agent, Zeta had 'replaced' her partner, and they would solve tech crimes every week in a Police Procedural.
- The creator, Robert Goodman, said season 3 would have revealed that Ro was unknowingly a robot.
- Word of God: Goodman and writer Joseph Kuhr confirmed in an interview that the synthoid hand in the last scene of the series is Andrea Donoso's, not Dr. Selig as some fans suspected.
Trivia / The Zeta Project