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.
YMMV: The Wonder Years
Confirmation Bias: A rather nasty case with Kevin's civics teacher. He does a number of prickish things, but Kevin only decides that he's irredeemably evil when it becomes apparent that he's a Republican.
Creator's Pet: Winnie is/was this to some people because of the way she treated Kevin.
In the episode "Heart of Darkness", Paul says that he's allergic to contact lenses, but in the last two seasons he switches to contacts.
Not to mention that in the episode before he starts wearing contacts, when Winnie informs Kevin that there's something he doesn't yet know about Paul, one of Kevin's guesses is that he's wearing contacts.
Built on a metric ton of these. Special stand-outs include the first episode's final revelation, Kevin's "I love you" to Winnie while she's sick at home, Kevin failing his piano recital utterly and admitting (in narration) that he doesn't even remember how to play anymore, and the Series Finale's ending commentary.
The entire Series Finale has to be one of the saddest, yet most enlightening in TV history.
Can't forget the time a teacher he was starting to bond with passed away.
They Wasted a Perfectly Good Plot: While it would have been hard to really focus on it since the shows entire focus was on Kevin and the last episode ended during the summer, it's a shame that they couldn't have shown Chuck and Jeff's summer road trip in the last episode, or even have the narrator reveal anything that happened to them on that trip.