When development for either a live-action film or TV series began when the first book came out in 1997, Dav Pilkey wanted Chris Farley to play Captain Underpants. However, Farley tragically passed away, and the project was shelved.

Released on the year of the book series' 20th anniversary.

The last DreamWorks Animation film to be distributed by 20th Century-Fox before Universal Pictures took over.

'Weird Al' Yankovic, who sings the theme song, is mentioned in several of the source novels, including the first one.

The school around which the film's actions are centered is named "Jerome Horwitz Elementary." Jerome Horwitz is the birth name of Curly Howard of The Three Stooges fame.

The shot of the school children marching sadly into school in the rain is an homage to the shot in Joe Versus the Volcano (1990) of workers marching slowly in the rain into a factory. That scene in turn references a scene in the sci-fi classic Metropolis (1927), in which workers march like automatons into the factory.

This is the sixth Dreamworks movie to be adapted from a children's book, the first five being Shrek (2001), How to Train Your Dragon (2010), Rise of the Guardians (2012), Home (2015), and The Boss Baby (2017).

This will be Dreamworks Animation's 31st film adaptation.

The subtitle for the film says "The First Epic Movie," despite no sequel announced yet. This is because the books had the subtitles "The First, Second, Third, etc. epic novel."

Unlike all of the previous DWA films, which were animated in-house in Los Angeles, this is the first to be outsourced; it was done at a lower-budget company in Montreal, Canada.

During the puppet fantasy sequence where George and Harold bump into each other, store names at the mall include "24 Hour Bunion Removal" "Everything Except Fabric Softener", "Fake Plant Paradise", "Monocle Mania", "Edna's Brazziers" "Lots and Lots of Phones", and "Robot & Wizard Supply".

The first film adaptation of a Dav Pilkey book, though it is based on several of the "Captain Underpants" books.

When George and Harold find a drawer to the confiscated items dedicated to themselves, it is indeed an ode to Harry Potter novels in which Fred and George find a drawer dedicated to themselves in Filch's office.

This will be DreamWorks' first superhero movie since Megamind (2010).

This will be Nick Kroll's third animated movie since Sausage Party (2016) and Sing (2016).

Despite positive reviews, this film only made $125.3 million worldwide, making it Dreamworks Animation's lowest grossing figure since Spirit: Stallion of the Cimarron (2002). This was probably because it's release coincided with that of Cars 3 (2017) and Despicable Me 3 (2017), sequels to popular animated franchises. On the opposite hand, Dreamworks Animation's other 2017 Film The Boss Baby (2017) received negative reviews, but grossed $175,003,033 worldwide, and spawned a sequel for 2021.

Kevin Hart and Ed Helms previously starred together in Meet Dave (2008).

Ed Helms' second Dreamworks Animation Film after Monsters vs. Aliens (2009).

This will be the second time Kevin Hart is a voice in an animated movie. His first time was in The Secret Life of Pets (2016).

This film went on to be nominated for the Annie Award for Best Voice Acting with Nick Kroll, the voice of Professor Poopypants, making this the first Dreamworks Animation film to have its antagonist nominated since Rise of the Guardians (2012) with Jude Law as Pitch Black.

Ends DreamWorks Animation's 17-year long streak that began with The Road to El Dorado (2000) until this movie came out, because of three 2018 movies being scrapped or pushed (Larrikins scrapped, How to Train Your Dragon: The Hidden World (2019) pushed, and The Croods 2 (2020) scrapped before continuing production, therefore being pushed), thus making 2018 their first year to not have any new films.

Kevin Hart, Ed Helms, Nick Kroll and Kristen Schaal each did voice work at Illumination.

Ed Helms and Leslie David Baker starred in The Office (2005).

First, and official, trailer for the film released the day after the DVD release of Nick Kroll's previous animated film, Sing (2016), where he also spoke with a German accent.

Kristen Schaal's fifth animated film after Shrek Forever After (2010), Toy Story 3 (2010), Despicable Me 2 (2013), and Cloudy with a Chance of Meatballs 2 (2013). It's also Schaal's first animated film to not be a follow up to a previous film.

Dreamworks Animation's 29th PG movie, of which all their films but Chicken Run (2000) and Spirit: Stallion of the Cimarron (2002) have been rated.

The 18th Dreamworks Animation film to be nominated for the Annie Award for Best Voice Acting, after The Prince of Egypt (1998), The Road to El Dorado (2000), Shrek (2001), Shrek 2 (2004), Wallace and Gromit: The Curse of the Were-Rabbit (2005), Over the Hedge (2006), Flushed Away (2006), Bee Movie (2007), Kung Fu Panda (2008), Monsters Vs. Aliens (2009), How to Train Your Dragon (2010), Shrek Forever After (2010), Kung Fu Panda 2 (2011), Puss In Boots (2011), Rise of the Guardians (2012), Turbo (2013), and Trolls (2016).

David Soren's second directorial effort for a Dreamworks Animation film, after Turbo (2013).

Ed Helms (Krupp/Captain Underpants) and Kristen Schaal (Edith) both have their birthdays on January 24th, with Helms being 4 years older than Schaal.

Thomas Middleditch and Kristen Schaal have also done voice work on animated Disney shows.

Jordan Peele's second animated film, after Storks (2016), another film where he voiced one of the villains.

Kristen Schaal's 2nd Dreamworks Animation film, after Shrek Forever After (2010).

Dreamworks Animation's ninth film to take the name of the main protagonist(s), after Shrek (2001), Spirit: Stallion of the Cimarron (2002), Sinbad: Legend of the Seven Seas (2003), Megamind (2010), Puss in Boots (2011), Turbo (2013), Mr. Peabody & Sherman (2014), and The Boss Baby (2017).

Ed Helms' 3rd Animated Film, after Monsters vs. Aliens (2009) and The Lorax (2012).

The second collaboration of Ed Helms and Nick Kroll, the first being Vacation (2015), which featured Peele's on-and-off partner Keegan-Michael Key.

Released five years after Ed Helms' most recent animated movie, The Lorax (2012), which was also based on a children's book.

Is the 3rd Dreamworks Animation film that's not a sequel to be subtitled, after Spirit: Stallion of the Cimarron (2002) and Sinbad: Legend of the Seven Seas (2003).

During the Flip-O-Rama segment, as Harold steps on the book pages, his footprints leave marks that closely resemble the guide areas in the actual Captain Underpants books, in which the reader places their hands in order to properly flip through the pages.

In the novel, Professor Poopypants' full name is Pippy Pee-Pee Poopypants. This is changed in the film to the even ruder Pee-Pee Diarrheastein Poopypants.

When Captain Underpants (disguised as Mr. Krupp) puts his head in the cotton candy machine, the cotton candy resembles the Electro starfish mask from Marvel's Spider-Man comics.

Melvin is the seventh character in a Dreamworks Animation film to be a hidden secondary antagonist, where he changes over to the side of the villains. The previous six films where someone does something like that are Shark Tale (2004) with Lola, Shrek the Third (2007) with Rapunzel, Puss in Boots (2011) with Humpty Dumpty, Turbo (2013) with Guy Gagne, How to Train Your Dragon 2 (2014) with the Muddy Bewilderbeast, and Trolls (2016) with Creek.