This episode was originally supposed to air on February 12th 2000 but the WB cancelled the show too early. But it did air it's only new episode on Cartoon Network on December 13th 2002.
The two series finales, "The Tail End" and "This is the End" was originally scheduled to air on Kids' WB! on February 12, 2000 followed by the movie Tweety's High-Flying Adventure (2000) released seven months in September 2000, but the network cancelled because it was too early. However, a rerun of the original unaired series finale that aired on Cartoon Network on December 13, 2002, two years after 'High-Flying Adventure', where the AOL Time Warner logo is shown.
One of the doctors in "The Tail End?" is based on the character design of the doctor in the Looney Tunes short Hot Cross Bunny (1948). Also, the mouse in the same short is based on Sniffles.
Cool Cat cameos: As an amoeba in "The Tail End?" at 5:20; auditioning for a Tweety replacement in "This is the End" at 15:05.