These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Discredited Meme: The "Garfield [something that sounds like minus] Garfield" bit after one use too many. It was officially axed when they made a strip with the Terminator going back to stop the meme's creation.
This strip became this when the real strip really did have a strip◊ about Garfield chasing a laser pointer two months later.
Similarly, this strip features Garfield paying Odie like a hitman to knock the head off a snowman, which became much less absurd when the actual canon◊ featured Garfield doing the same to an unnamed dog to sic Nermal.
The annotation of #88, a recreation of a mezzacotta comic, states "The next trick will be turning Garfield and Jon into Lightning Made Of Owls characters." They don't turn into them, but this comic was made a year later.
In this strip, the author points out that, despite his expectations, editing the strip where a mouse declares Jon's house part of "the Empire of Mice" to have the mouse representing various other fictional empires looked like it would never become a meme. The very next day, this was posted. And both author's notes end with a slogan praising the ruler of the empire featured in the strip. (In case you're wondering, the second strip couldn't have been made in response to the first due to the lead time caused by the Strip Buffer).
Even better, this contribution was posted a few weeks later, which had been submitted before either of the above.