Annoying Laugh: An episode had the gang laughing at Sylvester's failures.
Argument of Contradictions: In "Did Not! Did Too!," Bugs Bunny and Lola have an argument over whose flag to plant in a block tower. They go to their rooms and have a "Did not! Did too!" argument over who asked who to help each other.
Bratty Half-Pint: Taz, is one of those guys who gets what he want by throwing a fit.
Broken Aesop: In one episode where they went apple picking, Melissa insisted to the others that her picking method was better than the others', at which point they decided to have a race to prove which was the best. It ended in a tie, giving the Aesop that everyone's methods of doing things should be respected. However, the farmer taught her that method, making the Aesop come off as "it's okay to ignore the advice of the local authority figure".
Call Forward: In the episode Duck Reflucks, there is a sequence in one point that is vaguely similar to Duck Amuck, but with the roles reversed, with Daffy being the tormentor and Bugs being the tormented. And earlier, Daffy even says "The scenery! Where's the scenery?"
In New Cat In Town, Sylvester looks at a electronic that tells about skunks. It shows Pepe Le Pew as an adult.
Death Glare: In "Pouting Match" Lola starts pouting whenever she doesn't get her way. When the other babies start using the same trick she ups her game by switching to Crocodile Tears.
Duck Season, Rabbit Season: Played with in "School Daze", where Daffy and Bugs are arguing over who gets to sit in back of the bus while pretending to play school. Bugs wins, of course. The original short is even referenced.
Fun with Flushing: The main characters wonder about the toilet in the bathroom and form their own theories about how dangerous it is, while Petunia assures them nothing is wrong. In the process, they panic when Petunia accidentally flushes it, and puts toilet paper to "Feed the monster," clogging it up. They accidentally leave her in and she comes out wet with toilet paper on her. When Granny shows her what the toilet is really for, and Petunia tells them, they don't believe her.
Growling Gut: Bugs and Daffy have this a few times during the series, and Taz in in song "Taz's Fridge is Falling Down."
I Got a Rock: Keeps happening to Daffy when the babies go trick-or-treating, even when he's trick-or-treating the same houses as the others.
Insult Comic: Melissa becomes one after seeing one on TV. It doesn't go well, needless to say.
Lighter and Softer: BLT is quite a radical departure from the wanton violence and other antics of the classic Looney Tunes, as well as Tiny Toons and Animaniacs. It's really an in-name only spin-off, considering how far the characters are removed from their signature personas.
Never Say "Die": Granny says her mother "lives a long way away from now" in "Mother's Day Madness".
Nightmare Fuel: In-universe. In "The Sandman is Coming", Granny tells the kids the story of the Sandman to explain the sleep in their eyes, unintentionally terrifying Daffy, who decides to Never Sleep Again. (And when he does manage to stay up all night and his friends have sand in their eyes anyway, he's even more frightened because he has no idea how the Sandman got past him.)
Nobody Poops: Downplayed; School Daze mentions they're almost potty trained, and in Flush Hour, Petunia tells them what the toilet is for after using it off screen:
Petunia: "It's diapers plus!"
The Napoleon: Tweety usually isn't bad tempered, though some episodes deal with disadvantages he has because of his small size.
Nonindicative Title: Initially, they were a lot like actual babies with the obligatory "What is that white, water-filled chair in the bathroom?" plot. But as the show ran, the only thing that kept them from being full-on kids is that they were under school age.
Shout-Out: In an episode, Granny reads a tale about four termites living in a terrace, named Tex, Chuck, Friz and Bobdidn't get it? The WB Animation studio at the time the first Looney Tunes shorts were made was called "Termite Terrace", and Tex Avery, Chuck Jones, Friz Freleng and Bob Clampett worked there.