Originally, "The Day the Earth Looked Stupid" ended with Kang and Kodos looking over the devastated Springfield and commenting, "This sure is a lot like Iraq will be." Due to negative criticism from pre-airing screenings, as well as the producers and writers agreeing the line was too on-the-nose, that line of dialogue was cut from the final episode.
Orson Welles narrates ever-stranger sound effects until his sound effects man walks out on him. This is a homage to the radio program A Prairie Home Companion (2006), where Garrison Keillor often works calls for outlandish effects into his narratives in order to show off the versatility of sound effects man Tom Keith.
This episode was leaked out onto the Internet roughly a week before the first official airing and that version didn't have the "scary credits" that the aired version did.
This is the third time Maurice LaMarche voices a character that narrates a The War Of The Worlds type invasion, similar to the infamous Orson Welles' radio play. The first two were in Animaniacs (1993) and Hey Arnold! (1996).
The voice Maurice LaMarche uses for Brain in Animaniacs (1993), Pinky and the Brain (1995), and Animaniacs (2020) is essentially the same as the one he uses for Orson Welles, as the voice of Brain is largely based on Lamarche's impersonation of Welles.