There are many HTTP status codes for different situations, but most writers only know two which are both Client Error codes: 403 Forbidden and 404 Not Found. They are often referenced as a joke or Genius Bonus, though the latter applies especially if writers do use a different code than the aforementioned 403 and 404. They can also be used as showing something being changed or refused for 403 and destroyed or unavailable for 404.
- Deus Ex: Human Revolution, at the Picus Office, Jensen tries to track Eliza Cassan (whom, unknown to him, is an AI). The first room he's lead to check is room 404. Unsurprisingly, he fails to actually find her there (finding only a hologram of her).
- Devil Survivor 2 ends its Game Over message with 403 Forbidden. The message often appears when a website's code is being rewritten. In the context of the game, the world is being altered. Its Updated Re-release Record Breaker goes for 404 Not Found instead, to signify the world being destroyed.
- Epic Battle Fantasy 5: Using a Limit Break that shows Earth in its animation after the Devourer's deleted the world will instead show the animation with Earth replaced with a black circle with a red outline and "ERROR 404: NOT FOUND" in red.
- The Impossible Quiz Book: After wiping the Impossible Quiz from history and ending the game, you're shown the message "Error 404 "The Impossible Quiz.swf" could not be found".
- Skullgirls has plenty of lines for combo ratings. 403 has "Forbidden" and 404 has "Not Found".
- Super Paper Mario: One of the lines Fracktail says after being corrupted is "404 computer hamsters not found".
- Go to a page that's not there on homestarrunner.com, and this will happen to you. Ow! My browser!