The Warner siblings are based in a roundabout way on senior producer Tom Ruegger's three real-life children. Originally, they were going to be ducks named Yakki, Smakki and Wakki, but this idea was canned (it was thought to be too similar to "DuckTales" (1987)), and the three were changed into platypi, then into Bosko-like inkblots. Along the way, they gained a female friend; finally, Yakki became Yakko, Smakki and Wakki were combined into Wakko, and the female friend was named Dot and made their sister.
Pinky and the Brain are caricatures of "Tiny Toon Adventures" (1990) storyboarder/writer Eddie Fitzgerald (II) and writer/staffer Tom Minton, respectively.
One of the regulars (Ralph the Guard) was a recurring character in the later episodes of "Tiny Toon Adventures" (1990); also, several other characters have made cameo appearances, and the theme song from it shows up occasionally as well. See also "Pinky, Elmyra & the Brain" (1998).
Kathryn Page, who is credited with all sorts of crazy things (see the Crazy Credits section), is really one of the assistants of the shows senior producer, Tom Ruegger.
The Pinky and the Brain sketch titled, "Yes, Always", was taken virtually word for word from a recording of Orson Welles doing a commercial and berating the director and his suggestions for Welles' delivery. In this recording, Welles uses some rather bad language, which was changed for the sketch.
Episode 99 was "The Animaniacs Super Special." There is a slot in the closing credits where strange messages are hidden and in this episode the message read, "If you thought this was something, wait till you see episode 100." There was no episode 100 and the show was cancelled after this episode.
Many different last lines were used for the show's theme song. The most frequent was "Here's the show's name-y", but others include "Shirley MacLaine-y", "Citizen Kane-y", "Tarzan and Jane-y", "Pinky and the Brain-ey", "Come back Shane-y," "Where's Lon Chaney?" and "Dana Delany." (When shown on Nicktoons TV, however, the line is always "Nickilaney").
After a few seasons the line "'Bill Clinton' plays the sax" was removed from the opening credits. It was briefly replaced with the line "We have wisecracks by the stacks", but it soon gave way to "We pay tons of income tax". In some cases "We have baloney in our slacks" was also used.
Nathan Ruegger's voice began to change while voicing Skippy Squirrel. Rather than recast the part, the studio began altering his voice recordings to make them sound higher.
When Tom Ruegger created Buster Bunny for "Tiny Toon Adventures" (1990) he wanted to create a catch phrase (to parallel Bugs' "What's up, Doc?"). All he could think of was the old vaudeville standby "Hello, nurse!" but that made no sense for the character. Now the phrase is used by Yakko and Wakko when greeting Dr. Scratchansniff's attractive assistant.
The CEO, Thaddeus Plotz's last name is Yiddish for "explode."
The water tower where the Warners live and many other features of the Warner lot are rather accurate representations of the Warner Studios lot in Burbank California. (Although, the real water tower is all gold, not red on top.)
During the theme song the characters proudly anounce that "We have pay or play contracts". This is a Hollywood term meaning the performer is paid whether or not he plays - this was a big deal in the days of contract studio players.
The Animaniacs theme is in part a satire of "This Is It", the theme song from "The Bugs Bunny Show" (1960). For example, Bugs and company sing "No more nursing, rehearsing a part. We know every part by heart." The Animaniacs sing, "The writer's flipped. We have no script. Why bother to rehearse?"
The "Pinky and the Brain" segment in which Brain goes on a TV quiz show to win $99,000 is a parody of a famous "The Honeymooners" (1955) episode in which Ralph Kramden was similarly defeated by his sidekick's assistance. In Brain's case, Ralph Kramden IS the answer.
In the opening of the Pinky and The Brain segments, Brain writes "THX=1138" on the blackboard. This is a reference to THX 1138 (1971), written and directed by George Lucas. Lucas is good friends with, Executive Producer for Animaniacs.
The Goodfeathers theme song is a parody of ‘That's Amore’ by Dean Martin.