Top 20 The Big Bang Theory Callbacks in Young Sheldon

In this episode from season three, Sheldon discovers that his mom has been hiding a letter from Caltech, offering him a spot at the university. Since he’s still a kid, Mary’s not exactly eager to ship him off to California by himself. This leads to a big argument when it’s revealed she kept the letter hidden from his dad, too. Father and son then team up to convince her, presenting a video pitch with a backdrop that seems rather familiar. Yes, in the future, Sheldon would start a web series about Flags that he’d present in a very similar manner. We also love the use of flags in his college pitch. Nice touch!

Sheldon’s time in Germany gets mentioned occasionally in “The Big Bang Theory.” While the details may not always line up (unless he goes back again), one thing’s certain: he spent a summer there with his mom. It all begins when Sheldon realizes he’s leaned too much on his child-prodigy status and needs to beef up his resume for grad schools—fast. Thanks to donations from people eager for a Sheldon-free summer, he flies off to attend a summer school program. Of course, adult Sheldon also leaves out a few key details, like how he was dubbed the class “Dummkopf” and the fact that he was tutored by an even younger kid genius!

Sheldon’s love for contracts is only rivaled by his obsession with rigid schedules. It’s no shock that his bathroom schedule started in childhood, though the real surprise is that Missy adopts it too when their house gets crowded. Anyway, we know adult Sheldon thrives on creating contracts—whether with his roommates, friends, or girlfriend. Back in season one of “Young Sheldon,” Connie gets upset with Dr. John Sturgis for going behind her back to confront Ira, who’s trying to win her over with gifts, and Sheldon, who’s been getting a little too involved. So, Sheldon comes up with a solution that makes everyone happy. Narrator Sheldon even mentions that he’s continued this tradition with his children.

Many of us first learned about Schrödinger’s Cat from “The Big Bang Theory,” and more importantly, how we could apply it to everyday dilemmas. When George takes his sons on a road trip to watch a shuttle launch, a car game turns into a conversation about the theory—or at least, an attempt. Sheldon tries to explain it, but Georgie’s more concerned with the cat’s name, much to his brother’s frustration. George manages to steer the discussion back on track, but by then, Sheldon’s well and truly over it. Honestly, we’re not sure why Sheldon got so frustrated when Penny didn’t grasp it right away—she understood it much faster than Georgie!

In season two of the prequel, Sheldon helps Missy with her math homework, turning it into an experiment. This isn’t the first time apes inspired Sheldon to play teacher. In “The Gorilla Experiment,” he teaches Penny “a little physics,” comparing it to Koko the gorilla learning sign language. In both cases, he records the session and proves that the teaching profession is not for him. He’s not too kind to Penny, who’s genuinely trying, but cutting the hair off Missy’s Cabbage Patch Doll? That’s just cruel. Maybe young Sheldon hadn’t yet heard of positive reinforcement. Still, if he’d used the same “motivation” on Penny, we’re sure the result would’ve been the same.

In “The Big Bang Theory,” Sheldon mentions coming home every day after school to watch Professor Proton. Sure enough, in the “Young Sheldon” pilot, there he is on the sofa watching, yes, you guessed it, Professor Proton. He’s even watching the episode with the potato clock experiment that both confuses and blows Penny’s mind in the original series. It’s not just that Sheldon enjoys watching the show, but he even wants to dress like his idol, too. Ahead of his first day in high school, he panics when his bowtie goes missing. Professor Proton isn’t the only one of Sheldon’s childhood heroes who gets a shoutout in the prequel.

As many fans suspected, “Young Sheldon” is revealed to be adult Sheldon writing his memoir. In the series finale, we see Sheldon’s home office, which is packed with “TBBT” Easter eggs. You’ll spot his Nobel Prize medal on the wall, the DNA model in the corner, and even Gollum on his desk. Sheldon’s spot is there too! It’s so filled with nostalgic items from the old apartment that you’ll need to rewatch and pause repeatedly to catch them all. Amy and Sheldon’s chats also bring back moments from the original series. While season four revealed they named their son after one of Sheldon’s favorite Leonards, the finale also tells us more about their daughter.

Of course, we couldn’t expand “The Big Bang Theory” universe without bringing in some of the original crew. We mentioned Amy showing up in the final episode, but we also hear her voice alongside narrator Sheldon on a couple of other occasions. Simon Helberg reprises his role as Howard Wolowitz, too, but more on that soon. One cameo you might have missed is Kaley Cuoco, who voices the swimming pool in Sheldon’s nightmare. While she’s not playing Penny, the pool brings all the sass we loved from her character. Also, like Penny, the pool is surprisingly skilled at nudging Sheldon out of his comfort zone, even if, in this case, it’s just in his subconscious.

In one of the parent series’ most iconic running gags, whenever someone questions Sheldon’s sanity, he usually replies, “I’m not crazy; my mother had me tested.” Mary even confirms this during one of her visits to Pasadena. In “Young Sheldon,” we see her take him to a therapist after Dr. Sturgis’ breakdown, just to put her mind at ease. There’s also the time his parents took him to a psychotherapist after he developed a food phobia from choking at breakfast—though he wasn’t technically “tested” then either. Still, Mary clearly had her concerns, and at some point, she had him officially tested. It’s too bad the series doesn’t give more context or explain why Mary decided to skip getting a second opinion.

Sheldon infamously has little respect for a few professions besides his own. Yet, he holds a particular disdain for both Geology and Engineering. Although Howard often feels the sting of Sheldon’s comments about his field, it turns out this has never really been about him —well, not at first. It all began with Sheldon’s engineering teacher, Professor Boucher, who relentlessly challenged him and pushed him to his limits. Just when Sheldon thinks he’s nailed the assignment, he gets locked out of class for being late. So, essentially, Howard has been bearing the brunt of a very old grudge. Perhaps even more surprising is that Sheldon’s contempt for Geology can be traced back to a girl.

In the pilot episode for “Young Sheldon”, viewers were treated to one of the first references to “The Big Bang Theory.” As Sheldon goes outside to “play”, he encounters Billy Sparks, a not-so-friendly neighbor. When Billy scares Sheldon with a live chicken, the protagonist runs frantically to the house while screaming in terror. Avid viewers of “The Big Bang Theory” will remember older Sheldon telling over-the-top stories about having been harassed by the one and only Sparks. We’d go on to see more of Sparks in the prequel series, but this sequence connects the two shows from the jump.

This entry is unique, because it’s a callback to a very specific location from “The Big Bang Theory.” When young Sheldon gets a chance to travel to Pasadena to see Stephen Hawking in the third season, we’re given a look into his future as he visits Caltech. While he and his father stand at an open doorway, the camera pulls back, and we see the cafeteria where countless debates would ensue between him and his friends. Fans always knew Sheldon would end up at the research university, so it’s extra nice to see the genesis of it all.

One of the best recurring characters on “Young Sheldon” is Paige Swanson, a friendly rival to Sheldon portrayed by the amazing McKenna Grace. An incredibly touching moment unfolds in season three, when Paige opens up to Sheldon about why she’s having a hard time. Though the protagonist could come off cold, we see his softer side as he expresses compassion for his friend. Then, he offers her something we all knew was coming. Indeed, over 12 seasons of “The Big Bang Theory”, we’d see him deliver such an offering to many friends, whether they wanted it or not.

We all need to take a break from our daily routines from time to time. Young Sheldon opts for a breather from science by taking in the likes of the “Lord of the Rings” books. In doing so, he becomes obsessed with picking apart the story’s inconsistencies. It’s here we see him in a dream sequence talking to himself as Gollum/Sméagol. On the surface, it’s a cute joke. But to the keen observer, it’s a callback to “The Big Bang Theory”’s season three episode where the boys fight over a prop ring from the films. More specifically, we’re talking about the moment when Sheldon peers into a mirror and sees Gollum looking back at him in a dream!

Writing a prequel comes with its challenges, especially when you have to stay true to the original series. Take “The Hot Tub Contamination,” where Sheldon explains to Penny why he always knocks three times. This doesn’t seem out of character for the George often described in the original series. However, it does feel rather off for the character we’d come to know and love in “Young Sheldon.” The show sparked hints of George’s infidelity through flirtations with his neighbor, Brenda, but it never went beyond that. Eventually, the writers found a brilliant way to write themselves out of this tight spot without totally backpedaling on Sheldon’s account.

Whether it’s a spot at the dinner table, cafeteria, or somewhere else, many people have a place where they prefer to sit. Of course, anyone who’s seen “The Big Bang Theory” is aware that Sheldon takes ownership of “his spot” to a whole new level on numerous occasions. His attachment to the seat at the end of the couch is no laughing matter to the man. So when he finds Tam sitting at the end of a cafeteria table on “Young Sheldon,” we’re given a callback to the original series. In a later season he also tells Dale to move, despite not actually wanting to sit down himself. In case anyone was wondering, Sheldon has been staying true to himself since he was young!

Unlike the infidelity subplot, this was one storyline that couldn’t be avoided. In “The Big Bang Theory,” we learn Sheldon lost his father at age 14, so we knew it was coming. The show built up to George’s fate through his recurring heart problems and narrator Sheldon reflecting on things he wished he’d said to his dad. When the tragic moment finally happened, it was even more heartbreaking than we could’ve imagined. It was already sad knowing Sheldon lost his father, but now it felt like we’d lost someone, too. At least “Big Bang” found a heartwarming way to bring George back when Sheldon needed him most. And here come the waterworks again!

Fun fact: “The Big Bang Theory” writer Stephen Engel has reportedly been credited as the originator of Sheldon’s famous “Bazinga” quip. He apparently used to use it himself before it was thrown into the show. Heard when Sheldon tells a joke or pulls a prank, it’s become perhaps the single most recognizable word from the show. So it’s no surprise that the prequel gave the legendary word an origin story. Sheldon’s younger self wanders into a comic store and finds a display filled with prank products from the “Bazinga Novelty Company”. The rest is history, as he begins to prank his friends and family, all while uttering his famous catchphrase.

Ask any fan of “The Big Bang Theory” to name five memorable things from the show. We bet “Soft Kitty” will make the list. Penny and Sheldon shared many memorable moments of either of them singing this cute lullaby to each other over the years. Fans were even treated to Sheldon’s mother, Mary, singing it to him. So when “Young Sheldon” finds himself bedridden and sick as can be, everyone watching knew exactly what Mary was about to do. As she sings the song to her son, fans everywhere are reminded of him laying in bed as an adult, convincing Penny to sing him to sleep. As it turns out, it’s quite useful when soothing babies, too!


Before we unveil our top pick, here are a few honorable mentions.

Meemaw / Moonpie, Various
Her Name May Be Connie but to Us, She’ll Always Be Meemaw

The Path that Led Sheldon to Theoretical Physics, “A Patch, a Modem, and a Zantac”
Can’t You Just Picture It? Sheldon’s Future Employers Ask What Motives Him, to Which He Responds…

Fear of Driving, “Poker, Faith, and Eggs”
While He Would Eventually Get His License, We Can Kind of See Why He Wasn’t Too Keen for All Those Years

Graphic Tees, “A Clogged Pore, a Little Spanish and the Future”
Sheldon Enters His Teens Years in a Flash… T-shirt That Is

A Wink to Blossom Fans, “A Race of Superhumans and a Letter to Alf”
Little Did He Know That One Day That Actress Would “Blossom” into His Wife!

Since “Young Sheldon” focuses on the titular character’s youth, it precludes him from being able to interact with his future friends. However, on the night of the final episode of “The Big Bang Theory,” “Young Sheldon” also aired their season 2 finale. And the prequel show gave us the greatest nod to the original we could’ve asked for. As younger Sheldon cries over being alone at his Nobel party, the scene transitions. We’re given a sneak peak at Leonard, Penny, Raj, Howard, Bernadette, and Amy, all as their younger selves. Sure, we already knew Sheldon wouldn’t end up alone. But who doesn’t get misty-eyed seeing all his greatest friends, knowing the best was yet to come for all of them?

Which “Big Bang” throwback hit your acoustic sweet spot? Let us know in the comments!