Okay, so let’s just put it right out there: anybody tuning into “Common Side Effects” probably expects funny, fast, and totally left-field twists with every new episode. What a lot of even the diehards might not know? Sometimes, those twists come to life because the people behind the microphones — Kieran Culkin, Emily Pendergast, and the rest — went fully off-script. We’re talking unscripted quips, on-the-spot rants, and all sorts of delightful improv that quite literally snuck its way into the final cut. Who knew so much of the spark would start in the sound booth?
When Kieran Culkin Leaves the Script Behind
Let’s just start with Kieran Culkin. The man has comedic timing that could eclipse even the most carefully written punchlines. During recording for season two, episode four, Culkin’s character was supposed to mutter a half-hearted apology for forgetting a coworker’s birthday. On paper? A no-frills moment. But in the booth? Kieran riffed, tossing in an outrageously convoluted made-up excuse about losing track of time in an existential daydream about yogurt expiration dates. The entire room erupted.
And here’s where things get fun — according to a recent Variety interview, the writers loved the impromptu monologue so much, they expanded the scene. It ended up sparking a new running gag about food-related time travel. Now, whenever Culkin’s character looks at a fridge, fans get ready for a wild tangent. All that, from a single unscripted line.
Emily Pendergast: Queen of the Over-the-Top Ad-Lib
And then there’s Emily Pendergast, stealing scenes with just a sigh, a gasp, or a sly turn of phrase. Fans still talk about her wild improvisation in season three, episode seven. Her character discovers her keys have vanished — again. It’s a simple moment, right? But Emily goes off the rails, launching into a three-minute, mock-tragic monologue about keys “abandoning their post” and the profound loneliness of being padlock-less. None of it made the script, but every word landed in the show.
Socials went nuts. That bit alone blew up on TikTok, with hundreds of users lip-syncing those melodramatic lines. Some sharp-eared Redditors dug into it, too, spotting tiny callbacks in later episodes, like her character rattling doorknobs just to “make the keys jealous.” Not only did Emily’s improv change the scene, people actually started rooting for the keys to get their own spinoff.
The Entire Cast Gets in on the Game
It’s not just Kieran or Emily driving these unscripted gems. “Common Side Effects” thrives on group improv, building some of the show’s best bits from those magical, you-had-to-be-there moments in the booth. Here’s the scoop: during the recording of that infamous group therapy scene (yes, the one in season two where nobody could keep a straight face), an unplanned flub turned genius.
One actor (no one’s saying who, but the internet suspects Sean Giambrone) absolutely mangled a tongue-twister of a scientific term. Instead of killing the take, the cast kept riffing off the mistake. Suddenly, everyone started making up ever-wilder fake science words. The writers decided to keep the whole run. By the end, the faux-word “glumpagus” was trending alongside actual show hashtags.
- Possible evidence? Check out this behind-the-scenes Instagram post where the cast cries with laughter over that scene.
- Fans now use “glumpagus” to describe anything unexplainable in the CSE universe.
How the Crew Keeps It Fresh: The Director’s Take
Improvisation on an animated series isn’t always a guarantee. It takes a brave director and a confident cast. Luckily, CSE’s creative team wants lightning to strike — every session. In more than one press chat, director Mel Stanley explained the secret: “We just let them run with it.” Scripts set the direction, sure, but what happens in the sound booth? That belongs to the actors.
Stanley told TVInsider the room rule: when inspiration strikes, nobody cuts until the joke falls flat, or someone actually falls down — that’s it. That freedom means the actors try anything, from wild character voices to over-the-top sound effects, sometimes turning a throwaway joke into the heart of the episode.
Fans Catch Every Wink, Nudge, and Wild Tangent
It’s one thing for the cast to go off-script, but another when the audience spots it — and loves it. Just check out X (the platform formerly known as Twitter) every Thursday night. The hashtags #CSEImprov and #UnscriptedGold fill with screengrabs, GIFs, and fans yelling, “Did you just catch what she said?” People eat up the unscripted moments, especially the ones that make characters feel real, weird, or even a little unhinged.
Let’s not forget Reddit, where fan detectives notice callbacks and improv flourishes that casual viewers might miss. They’ll dissect scenes, find early hints that only showed up because an actor ran with an idea, and sometimes even start full-blown discussion threads, like “Best Unscripted Moments: Which Voice Actor Deserves an Emmy?” (Spoiler: most say Emily.)
The Art and Science of Animated Improv
So why does improv work so well in animation, especially for “Common Side Effects”? Here are the secrets:
- Timing: Animated shows can tweak the visuals to fit a sudden improv, even weeks later.
- Chemistry: Voice actors riff off each other, and that spark makes the cast’s bond obvious even through your headphones.
- Authenticity: It’s easier to believe in a character who sometimes says something messy or weird. Real people mess up and joke, so animated ones should, too.
Industry insiders nod to animation’s improv roots — think Robin Williams cracking up the team on “Aladdin,” or the way “The Simpsons” let Dan Castellaneta and company spin wild new storylines from tossed-off ad-libs. On CSE, it’s no different: when actors make up lines, the animators jump in to match every “wait, what?” expression with perfect timing.
Breakout Unscripted Scenes Everybody Talks About
Here are just a few improvised classics, according to fresh August 2025 social buzz and interviews:
- Culkin’s Fridge Rant: A one-sentence apology grew into a running saga on expiration date paranoia.
- Pendergast’s Lament of the Keys: Fans are still quoting it, and you can buy “Padlock-Less and Proud” mugs.
- The Great Glumpagus Debate: One made-up word. Ten minutes of riffing. Endless memes.
Sometimes these off-script gems even spark new episode ideas. After the “lost keys” drama took off, showrunners confirmed a full-blown flashback episode — tracing the keys’ wild journey — hit the writers’ room, all thanks to Emily’s improv.
The Big Picture: Why Improv Keeps CSE Fans Hooked
With so many shows dropping each week, what keeps “Common Side Effects” feeling fresh? It’s this sense that anything could happen next. Maybe a voice actor drops a jaw-dropping one-liner, or maybe a minor screwup ends up as a fan-favorite joke. Scripted or not, nothing feels stale. The actors’ unpredictable voices keep the show’s heart beating and the fandom wild.
Plus, this culture of letting performers play around isn’t just a happy side effect (pun absolutely intended). It’s the fuel. The actors feel free to experiment, and in turn, the writers stay nimble, weaving those left-field lines into future storylines, background gags, or hidden easter eggs. So you hear something new — sometimes, something not even the crew expected — every single episode.
So, What’s Next in the Improv Universe of CSE?
With a cast addicted to riffing and a fanbase that can’t get enough, there’s no telling how wild the next batch of episodes will get. Will Emily give us a twelve-part saga about mismatched socks? Will Kieran turn breakfast cereal into an existential dilemma about adulthood? Odds are, the best moments ahead aren’t even on paper yet.
Keep your ears sharp, your hashtags ready, and, just maybe, start prepping your own fake science terms. If “Common Side Effects” has taught us anything, it’s that the weirdest, wittiest improv always sneaks up when you least expect it — and sticks around for seasons to come.
