D.J: What I really do is I... I'm a stunt man! Daffy: HA! You, a stunt man!? Please! D.J.: I am! You seen those Mummy movies? I'm in them more than Brendan Fraser is! (A lot of Fraser's commentary for the first Mummy movie is him pointing out stunts he didn't do.)
Taken to extremes when D.J confronts 'Brendan Fraser' and punches him out for getting him fired.
Creator Backlash: Since the film came out, Joe Dante has really only discussed this movie publicly just once. The one time he did all he could talk about was the Executive Meddling behind it, and "the less said about [the movie], the better." He did say though that "At least it's better than Space Jam".
Creator Killer: Warner Bros. Feature Animation, which had yet to produce a single financially successful film in it's barely-seven-year existence (mostly due to poor advertising and the studio only having a passive interest in animated features) finally collapsed after this film failed. The fact that it was released just as Hollywood was abandoning hand-drawn animation didn't help.
Franchise Killer: The faltering merger of Time Warner and AOL caused all official merchandise to end years earlier. But this film! This film put an end to any major Looney Tunes production for good... and only until seven years later would someone revive them into a television show!
Not only this, but one year after the film's release, the classic Looney Tunes shorts were canceled from Cartoon Network, and were not seen on TV for nearly half a decade until Cartoon Network slowly began to bring them back in 2009, only to end up removing the classic shorts again by 2016 (along with Wabbit: A Looney Tunes Production).
The Other Marty: A lot of voice actors were switched out by the time production ended:
Billy West was originally cast as Bugs, but halfway through, was replaced by Joe Alaskey.
Jeff Bennett originally recorded a lot of Daffy's lines before also getting replaced by Joe Alaskey.
Bob Bergen performed several of Tweety's lines, but the final film features animator Eric Goldberg in the role.
Maurice LaMarche recorded for Yosemite Sam, but his voice was weak from a previous project, and couldn't properly duplicate Sam's harsh vocals, and was replaced with Jeff Bennett.
Screwed by the Network: The film's failure probably can be blamed on when it was released and how Warner Bros handled it - while it's unknown how it would have faired if it had released in July as originally plannednote while the film would have had to have competed with Pirates of the Caribbean: The Curse of the Black Pearl and the third Spy Kids movie, there were no major animated films released during that month, due to the executives getting nervous about the success of Finding Nemo in May, it was pushed back to November, putting it a week after Elf, releasing it the same week as the critically acclaimed Master and Commander, and a week before The Cat in the Hat. This, combined with Warner Bros barely advertising the film, makes it no wonder why the film failed.
Talking to Himself: Brendan Fraser playing three different characters, one of them even punching another near the end. One of them is Brendan Fraser himself.
Not to mention Bugs and Daffy; both voiced by Joe Alaskey.
Throw It In!: Brendan Fraser kept imitating the Tasmanian Devil, so the producers decided to let him voice Taz.
What Could Have Been: The script went through at least five revisions, so a ton of content got changed or axed altogether.
Triple H was originally going to play Mr. Smith. They actually based part of his feud with Goldberg around this.
Originally, the movie was scheduled to release in July of 2003. However, it was pushed back to November due to Finding Nemo being a hit (which still ended up beating this film anyways.)
Instead of Brendan Fraser, Jackie Chan would have been the star.
The characters designs were originally going to use the early 40's Looney Tunes designs, but they opted to use the modern "on model" designs instead.
Joe Dante originally wanted more Hanna-Barbera characters to cameo in the film beyond Scooby and Shaggy to give the film more of a Roger Rabbit feel, but Warner Bros. said no to this.
Area 52 was originally just called Area 51 and at one point the whole sequence was planned to be cut from the film.
Pepe Le Pew was originally going to have more lines in the film, but his role was reduced to a very brief cameo instead.
According to the deleted scenes, the movie was originally to have a completely different opening and ending plot progression, the opening being a Batman parody while the plot itself would have stayed in the jungle and involved Tweety (who was apparently supposed to stick around with the heroes) to a greater extent.