Corrected entry: After Wile E Coyote fires the missile and it comes back and strikes him, the shot changes to the gang out in the open desert. Then there is the live-action explosion from the missile in the distance. The explosion was from an animated missile and should not have resulted in a live-action explosion.
Corrected entry: The only Loony Tunes character who does not appear in the film is the black and white cat that Pepé Le Peu chases in all his cartoons. In the 'Pepé Le Peu Warner Brothers' Studio Store Collectibles' we learn that her name is Penelope