Keep an eye out for some of these sightings found in the show...-Gaz
| Episode | Reference |
| The Nightmare Begins | The guy that does the "Old Kid's" voice is actually Jhonen Vasquez. |
| The Nightmare Begins | During the very beginning of the show where the alien announcer is shown on a screen, another screen floats behind him that shows the weird monkey-like thing on Zim's living room wall. |
| The Nightmare Begins | When Gaz opens the fridge a milk carton reads "Rob Hummel is Meat." |
| Walk of Doom | "Z?" shows up on a building. |
| Walk of Doom | Two gay men are standing and holding hands watching the Scary Monkey Show through a window in a store. |
| Walk of Doom | Filler bunny shows up near the steering wheel on the bus that ZIM rides on. |
| Walk of Doom | Two signs are on a building when ZIM and GIR are riding the bus. One reads: "Stop making babies" and the other one says "The goat whats you" I don't know if it was really supposed to say "The goat wants you"? |
| Dark Harvest
| Filler Bunny is in a test tube, then broken in half by a ball that comes in through the classroom window. |
| Dark Harvest
| When Dib is running through the hallways, there is a little sign on the wall that says "JV" which are Jhonen's initials. |
| Attack of the Saucer Morons
| The guy that prophesized the coming of the "aliens" was Frank Conniff from Mystery Science Theater 3000, and also helped with writing ZIM. |
| The Wettening
| Jhonen appears, sitting on his couch reading a comic, and his shirt reads: "Z?" He then chokes on a goldfish. |
| The Wettening
| In the part where Jhonen chokes on a fish, the scary monkey thing that is on ZIM's wall is backwards behind Jhonen's aquarium. |
| Almost all of the episodes
| Roman Dirge is seen walking down streets and sitting in restaurants occasionally. |
| Almost all of the episodes
| Jhonen and Steve appear many times throughout the show. |