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.
Creator's Pet: Chett. The producers liked Lee Tergesen's Large Ham performances so much that they started writing bigger and bigger parts for Chett, eventually making him a Secret Keeper in the final season.
Growing the Beard: Starting in the second 13-episode season (when Wyatt's hairstyle changes) the writing improved considerably, moving away from the premise of the movie toward more fanciful magic and sci-fi adventures, and giving Chett more to do than just be the Butt Monkey.
In "You'll Never Eat Brains in This Town Again," while trying to coordinate a stunt, Chett kicks a zombie's head off - except he thought it was just a student actor and subsequently thinks he killed someone. While trying to bribe Wyatt into not testifying against him, a panicked Chett exclaims, "I can't go to prison!" Turns out, he did go to prison.
In the second episode, Wyatt and Gary get a hold of a universal remote that allows them to control time. Sounds familiar.
Justified in that Gary and Wyatt are extremely socially awkward and didn't exactly think that it would work.
On the other hand, Wyatt wakes up wearing Lisa's underwear. While it's strongly implied that they might have had sex, she claims he passed out before they did anything. Maybe the underwear was a joke on her part, as it gets him in trouble with his older brother, or she could have denied it to avoid embarrassing him; it's up to the viewers to decide.
Signature Scene: Lisa's first appearance and first words: "So, what would you little maniacs like to do first?". This is the scene most frequently parodied.