John Cleese made a brief cameo in the film at one point during the Paris sequence, but his cameo was cut out because it didn't have anything to do with the film. Also, the reason Scooby-Doo and Shaggy make cameos in the film, even though they are not Looney Tunes, was because director Joe Dante wanted some non-WB characters in the film like Tom & Jerry, and Droopy, but WB thought that would be too weird, so they told him a Scooby-Doo cameo would seem more "appropriate". If one looks closely, the animation of Scooby and Shaggy is stiffer and more limited than that of the Looney Tunes characters, referring to the drastically cheaper budgets of the Hanna-Barbera studio at the time the original Scooby series was created.
Elmer Fudd chases Bugs and Daffy through three of the world's most famous paintings: "A Sunday on La Grande Jatte" by Georges Seurat (displayed at The Art Institute of Chicago), "The Persistence of Memory" by Salvador Dalí (Museum of Modern Art, New York) and "The Scream" by Edvard Munch (Oslo's Munch Museum. On August 31, 2006, Norwegian police announced that the painting stolen in August 2004 had been recovered.).
In the spoof of the Psycho shower scene Bugs pours a can of Hershey's chocolate syrup down the shower drain, a reference to the fact that Alfred Hitchcock used Bosco's chocolate syrup in the original scene to better simulate blood in black and white.
Porky Pig and Speedy Gonzales are seen in the restaurant discussing how political correctness has affected their careers. Both characters have come under fire for insensitivity in recent years. Porky for his stutter, and the Looney Tunes and Merrie Melodies shorts that featured Speedy Gonzales were pulled from the Cartoon Network's daytime and prime time line-ups. It was alleged that Speedy was "racially offensive" to Mexican people, a point which became moot when some representatives of the Latino community organized a movement to get Speedy back on the air.
Lola Bunny, introduced in Space Jam, does not make an appearance, but can be seen on several movie posters in the background of some scenes. The existence of Lola's character, created as a "politically correct" counterpart for Bugs is spoofed when Kate suggests that what Bugs needs to "leverage his synergy" is a "hot female counterpart." (see quotes section)
The character animation of the Warner Bros. cartoon characters in this film is traditionally hand-drawn. Computer technology is used to color the animation drawings in, add tone mattes/shadows to the characters, and composite them over the correct backgrounds. 3D Computer animation is used on objects such as the spaceships, Wile E. Coyote's missile, the robot guard dog at the end, and Bugs' cel-shaded carrots.
At the end of the movie, Bugs gets into a limousine and is handed carrots by numerous minor characters from past "Looney Tunes" and "Merrie Melodies". Among them are Charlie Dog, Heathcliff (from the Arthur Davis short Dough Ray Me-ow), the Squirrel (from the Chuck Jones short Much Ado About Nutting), Gruesome Gorilla (from the Robert McKimson short Gorilla My Dreams), Hippety Hopper, Marc Antony, Pussyfoot, and Egghead (the forerunning character to Elmer Fudd).
In the casino, while D.J. is fighting with Yosemite Sam's goons, Daffy tells him to "bite his ear!" This is a reference to boxer Mike Tyson, who bit off a portion of Evander Holyfield's ear during a match.
When Elmer Fudd is chasing Bugs and Daffy through the museum, the music playing is from the piano suite "Pictures at an Exhibition" by Modest Mussorgsky, a cycle of piano pieces describing a walk through an art gallery (by a man with a limp) and the different paintings he stops to look at.
The last film Jerry Goldsmith would score. Due to Goldsmith's failing health, the last reel of the film was actually scored by John Debney, though Goldsmith was the only credited composer in marketing materials. Debney got a small credit at the end as "Additional music by".
Steve Martin read the script and would only do the film on one condition, in the scene where aliens chase Daffy Duck and Bugs Bunny, a Dalek ( from Doctor Who) is one of the aliens used. Warner Bros. accepted.
When we first See Dusty Tails (Heather Locklear), she is wearing a Southern Belle-type dress and hat, and being lowered from the rafters on an ornate, vine-covered swing. This is a nod to a scene from Walt Disney World's "Country Bear Jamboree" attraction, where the animatronic character "Swingin' Teddie Berrah" is lowered from the ceiling wearing a similar dress and hat, on the same type of swing. Even Foghorn Leghorn's introduction for Dusty mimics the MC's intro for the Walt Disney World character.