God admitting that "our computers are on the blink" when he explains that he doesn't know what life Garfield was on.
Garfield pretending to think when asked, with a hilarious Aside Glance to the audience
Odie "meowing" when God asks if he's a cat too.
How Garfield lost his first life in Cave Cat: a gargantuan dinosaurian Odie called "Big Bob" tore apart the largest and apparently last tree of the time, and wanted to play fetch with it. Big Bob spat it out onto him and crushed Prehistoric Garfield, with only his saber teeth poking out of it.
In Cave Cat, Prehistoric Garfield bumped into a caveman's leg, and the caveman yells "Cat!" The narrator says that cat was the caveman word for "Ouch!"
The "decapitation slideshow" by the jester in Court Musician. Particularly the Embarrassing Slide.
Ancient Egypt Garfield seeing a lit dynamite stick. "What is this? *tossing away* Whatever it is, it hasn't been invented. *BOOM!* But seemingly it does work..."