|The voice of GIR is provided by Jhonen's friend, Rosearik Rikki Simons. Simons does the coloring for Jhonen's color comic books and the coloring design for "Invader ZIM".|
|Johnny the Homicidal Maniac (one of Jhonen's comic book characters with quite a loyal fan base) gets several references throughout the series. He appears twice in "Halloween Spectacular of Spooky Doom" with bright purple eyes and striped horns and has been lovingly dubbed "Nightmare Nny" by fans. In "Tak, the Hideous New Girl", Tak wears his boots.|
|Four completed, unaired episodes were left hanging in the balance when Nickelodeon canceled the show. Those episodes are titled "Backseat Drivers from Beyond the Stars" (#2.1), "Mortos Der Soulstealer/ZIM Eats Waffles" (#2.2), "The Frycook What Came From All That Space" (#2.3), and "Vindicated!/The Voting of the Doomed" (#2.4). All four were included on Volume 3 of the Invader ZIM DVD release.|
|In the episode "A Plague of Babies", the goth vampire from series creator Jhonen Vasquez's "Meanwhile..." comic is visible in the background of the first baby's house.|
|# Bloody GIR is an Easter Egg visible in several episodes of the series. To see him, one would likely need a DVD player capable of viewing screens frame by frame. The most visible instance of bloody GIR is in the opening sequence of Mortos der Soulstealer. The image is evident for at least two frames in the end of one of the pipes that snakes out of Zim's house. Bloody GIR has also been sighted in Bad, Bad Rubber Piggy as the last pig goes through the "space time object replacement device". He has also been seen in the voot cruiser sequence in the opening of Plague of Babies. He is seen looking in the window of the voot at the left hand corner of the screen several times, some more noticeable than others. Bloody GIR was born when Jhonen drew an image of GIR covered in blood. He wanted to make an episode that featured bloody GIR but Nickelodean would not allow it. He decided to slip the image into several episodes without their knowledge.|
|The producer, Steve Ressel, appears in some episodes, in cartoon form. He is the fat man with long black hair and glasses.|
|The creator, Jhonen Vasquez, appears in some of the episodes, in cartoon form. He is the tall man with orange spiky hair and glasses.|
|In the episode "The Nightmare Begins", when Zim is picking a disguise to use on Earth he claims one is "too ugly" and another "too stinky". Those disguises are pictures of Jhonen Vasquez and Steve Ressel respectively; two of the creators of the show.|
|The original name for Zim's ship was to be the "Spoot Cruiser" but the phrase spoot had already been made big in "The Angry Beavers" (1997), so they made it the "Voot Cruiser" instead.|
|The show frequently has Jhonens Vasquezes characters from his comics in the background.|
|The vampire featured in the game Gaz is playing on GS2 is D from the Vampire Hunter D movies.|
|Before Richard Steven Horvitz got the job, Mark Hamill and Billy West were hired to voice ZIM. At the time, Horvitz was doing the voice for Dagget on "The Angry Beavers" (1997), and Nickelodeon didn't want the same actor on two current shows. Hammill originally voiced ZIM for the pilot episode. When Hammill was dropped, his parts were dubbed over with West's voice. The creators decided that both Hammill and West were too well-known, and finally hired Horvitz when the "The Angry Beavers" (1997) series ended.|
|Frequently, after GIR drinks something, he launches into an inexplicable coughing fit. What you hear are actual recorded real-life coughing fits of GIR's voice actor, the asthmatic 'Rikki Simons' , who could not perform GIR's enthusiastic slurpy drinking noises without aggravating his breathing.|
|Jhonen Vasquez asked the animators to stop putting cameos in the series after about episode 10. He felt that the cameos drew attention away from the show and that people would only watch for the cameos. Vasquez's creations (comic characters, Z?, references to his other works, etc.) still continue to appear, but no more Jhonen.|
|If the show had not ended, the following events and stories would have taken place:|
* Invader Skoodge would have moved in with Zim on earth
* Dib would have discovered he is a clone of Professor Membrane and not actually his son.
* Tak would have returned.
* Zim and Dib would have left Earth and had a season where Dib chased Zim across the galaxy on their way to Irk.
* The Resisty would have returned
* And a series finale move entitled, Invader Dib, which would have had a full scale war against the Irkens.