The Reads are going to a family reunion at their great uncle's farm for his birthday, and also bring Buster along. Arthur is excited to see his cousin Ryder after four years, but upon actually meeting him, he discovers that he and Ryder don't have as much in common as he thought. Meanwhile, D.W. continuously runs into a lizard she's scared of, and Buster feels like he doesn't belong at the reunion due to not being a Read.
The Rhythm and Roots of Arthur contains examples of:
- Are We There Yet?: D.W. asks this during the trip to the farm, and even gets a song about her boredom.
- Birthday Episode: This episode takes place on great-uncle Theo's 85th birthday.
- Brutal Honesty: During the trip to the farm, D.W. rather bluntly asks why Buster was brought along to the family reunion, since he's not a Read and doesn't even look like one.D.W.: I'm not being mean! I'm just telling the truth.
- Call-Back:
- D.W. still has her puffin toy and Rapty, both of which she brings with her to the reunion.
- Buster's mom packs an inhaler for him for the trip due to his asthma.
- When Great Uncle Theo asks D.W. if she likes spinach, she sticks out her tongue in disgust.
- Arthur and Buster play checkers together, which they were already shown to enjoy in "Buster's Back".
- Arthur tries to scare away the owl in the barn using the same nonsense words Kate heard D.W.'s words as in "Baby Steps".
- Comic-Book Time: Arthur comments that it feels like 3rd grade has gone on forever. Interestingly, D.W. is implied to be 5 in this special, making this an aversion; she still has the puffin toy she got for her 5th birthday in "D.W. and the Beastly Birthday."
- Continuity Nod:
- After Buster's bag falls off of the roof of the Reads' car, a racoon finds his bathing cap in it.
- In the farmhouse, a photo of a young Thora holding Clarissa can be seen.
- Early-Bird Cameo: Aunt Minnie has a minor role in this special. Come An Arthur Thanksgiving, and one sub-plot completely revolves around how D.W. isn't familiar with her.
- Foreshadowing: Cousin Miles being a rabbit, rather than an aardvark, is an early hint that he is not actually related to the Reads.
- Furry Reminder: D.W. telling Buster that he doesn't look like the Reads is a possible one.
- Glowing Eyes of Doom: The owl in the barn that Arthur and Ryder sleep in has these, which unnerves Arthur so much that he is unable to sleep. Subverted since the owl isn't actually dangerous, just creepy.
- Homesickness Hymn: Buster doesn't feel like he belongs at the family reunion, while D.W. is bored. They sing a song about how they want to go home, but midway through, realize how cool the reunion is and that they'll stay for a bit longer.
- Lampshade Hanging: When Ryder tells Arthur and Buster that he's entering fourth grade soon, Arthur asks if it feels like third grade has gone on forever.
- Leaning on the Fourth Wall: The unnamed old woman's line "Hey Lorraine, [Buster] is on some show called Arthur!"
- Musical Episode: Four songs are sung throughout the course of the special.
- Never Say "Die": Averted when Theo outright tells D.W. that his sister died before D.W. was born.
- Never Trust a Title: While Arthur is a major character in this special, it mainly focuses on D.W. and Buster.
- No Name Given: The older woman at the reunion who has hearing problems isn't named in the special.
- Ominous Owl: The owl in the barn has scary glowing eyes and unsettles Arthur with them and its cooing so much that he is unable to sleep.
- One-Steve Limit: Averted, as this special reveals that D.W. was named after Theo's sister, whose full name was also Dora Winifred Read. At the end, D.W. also names Bernice the llama's cria "Dora".
- The Reveal: This special reveals the origins behind D.W.'s name: she was named in honor of Theo's sister, who passed away before D.W. was born.
