From the ending of "First Day of Rule" when Elena inducts Naomi into the Grand Council. What makes it even funnier is that she chooses Naomi before she also tells Esteban that he's also in the council too:
Meta: According to Craig Gerber in an interview with the Podcast Princesses, this became an inside joke among the crew, where Naomi saying "me" in the script would immediately have someone chime in with a "Her?!".
From "Model Sister":
Esteban: Once King Toshi sees how well I know his ways, he will entrust me to make the trade agreement, and it will be clear to everyone who is the real power behind the throne.
In "Model Sister," when Elena's sister Isa asks her why she changed clothes, she replies "Uh, wardrobe malfunction?"
In "Spellbound," when Elena and her friends discover that the entire ballroom has been Taken for Granite, Naomi accidentally snaps off half of Esteban's moustache, then sheepishly puts it on his shoulder. It becomes a Brick Joke once everyone is restored; Esteban makes to stroke his moustache, then realizes half of it is missing.
Zuzo's "advice" on how to deal with Orizaba in "The Scepter of Light":
Zuzo: First, we're gonna start with a few cleansing breaths. (breathes in and out) Feels good, doesn't it? Now slowly, gently... get used to living in a world of total darkness. Elena: What?! Zuzo: Oh, it's not so bad. Just think of it as a non-stop slumber party!
"Spirit Monkey Business" has the spirit guides explaining their roles as guardians and advisors. One darts off to help someone with a math problem, one helps another get over his fear of heights, and the third realizes her charge has fallen into a pit of snakes.
The same episode also features Esteban finding an oddly specific chapter titled "How To Remove a Stuck Helmet"note His Abuelo put on a helmet from a suit of armor which he couldn't remove
"My Fair Naomi" has Naomi telling Elena to wear an ugly pink ruffly gown for her birthday party. When Naomi and Esteban leave Elena and Luisa alone, Elena tells her grandmother that she's going to ask a question and needs her to be honest only for Luisa to give her answer before Elena even asks her.
Elena: Abuela, I'm going to ask you a question, and I need you to be honest.
Luisa: It's hideous.
"Elena and the Secret of Avalor" has Elena singing "I have a plan that can't fail" in the song "My Time". Why is this funny? Because Elena's plan to stop Shuriki was just walking into the throne room, and unsurprisingly, the plan does fail.
This gem from "A Day to Remember" :
Carmen: I'm an artist, Julio! The plate is my canvas, the food my paints!
Julio: Sometimes it does taste like paint.
"The Curse of El Guapo" has Gabe getting possessed by "El Guapo", the spirit of a master soldier who's also a ridiculously Large Ham that makes Spanish Buzz look subtle. Just seeing the bemused Gabe alternate between the two is hilarious, including one moment when Guapo gets control of his feet while Gabe has the upper body and is trying to slow them down.
"A Spy In The Palace" has Victor and Carla rapping . It's hilariously terrible. That is all.
In "Flight of the Jaquins", Skylar's younger brother Nico reveals that they once pranked their father, King Verago, by taking apart their nest at home and rebuilding it upside-down while the latter was sleeping in. Ciela deems this impossible as Verago would've fallen out only for Nico to reveal that he and Skylar tied him to the nest with vines! The thought of this prank is a real rib-tickler.
When Victor and Carla, both in disguise, meet in the marketplace in "Science Unfair", and almost blow each other's covers:
In the same episode, the fact that Migs calls Dulce "Pookie-face" is hilarious in and of itself. But once she overhears this, Lunawon't stop using it on him.
There's also the fact that during "Right Thing to Do" Esteban, while trying to convince Elena not to go after Shuriki and the Council to decree she stay in the palace, manages to fit his Catchphrase ("This is true") seamlessly into the song.
In "Race for the Realm", Victor and Carla are finally made into Malvagos by Fiero. Victor assures him "You will not regret this!" as he and Carla prepare to take off in their horse-cart...only to show they have no idea how to drive it and go way too fast down the road.
In "Song of the Sirenas", Elena accuses Cristobal of betraying his family. Cristobal responds by starting up the cliche line that "betrayal" is such a strong word and that he would call it...and then he fumbles for a while trying to think of something before conceding that no, "betrayal" pretty much sums it up.
When trying to break the royal family out of the prison on the jaquins, Mateo asks who wants to go first, and Esteban immediately says "Me! Me!" before sheepishly letting Isabel go first, though Mateo gets both of them anyway.
One of the shorts, "Marisa And The Mirror", has her coming across a broken mirror in a shipwreck. Since she's never seen one before, she is understandably confused yet also cute when doing so. She then proceeds to make a bunch of silly expressions, which makes Elena laugh with her.
They almost get attacked by a shark, but are saved when he starts looking at the mirror.
At the end of "Blockheads", Franciscio, Luisa, and Esteban return from Cordoba and notice that Elena, Isabel, Mateo, Gabe, and Naomi had been playing Olaball indoors, and it seems like Luisa is going to scold Elena for being careless, but it turns out she's only upset that her granddaughter was playing Olaball without inviting her abuela, not even caring that they knocked a hole in the wall.
Mateo trying to tell his mom that Elena has shown him the Royal Sorcerer's Quarters... which she surprisingly reacts to in glee, as she knows it means Mateo has been invited to stay in the palace. The next morning, she's all packed and it turns out she thought that she was also invited.
Rafa placing houseplants around the palace, which is always immediately followed up by Esteban walking in and expressing disgust at it before trying to hide it, like behind a curtain. When Elena and Mateo greet Rafa goodbye, Esteban dashes out the door with one of her houseplants, begging her to take it with her, only to be too late as she leaves the palace grounds in her carriage, causing him to yell an skyward "No!". As the episode closes, Esteban drops the plant from a high window and only the sound of a broken vase is heard.
Rafa cleans the family picture plates hung in the dining room, but offsets Esteban's. Right as Esteban tries to remove the houseplant on the dining table, his attention is immediately switched to his offset plate, which he tries to fix, only for it to break in half.
Rafa pestering the royal chef about what food to serve to Mateo.
Rafa saying that she doesn't want to leave Mateo all alone from the dangers of the modern world in the palace, which includes exploding potions, dangerous spells, and "that horrible Esteban". Keep in mind that she's never had a direct interaction with Esteban in the show.
As Elena and Mateo leave the Royal Sorcerer's Quarters after resolving to talk to Rafa about her unpopularity with the staff, Esteban, Armando, and the royal chef are all crowded at the door with their complaints.
Someone called Esteban an asshole on Twitter. Christian Lanz's response?
Christian Lanz (Esteban's voice actor): That's Chancellor Asshole to you!