- Approval of God: Despite receiving an executive producer credit, Dav Pilkey was decidedly hands-off with the production and only gave direct approval of the first draft of the script. In his words, he wanted to "experience Captain Underpants as a fan" (not to mention he didn't want to call the shots in a medium he had no experience in). He would go on to give the movie glowing praise◊, particularly to Mr. Krupp's Character Development.
- Ascended Fanon: Considering that Word of God revealed the Significant Birth Dates that some of the characters have (i.e. both Mr. Krupp and Professor Poopypants birthdays being April Fools' Day, and Melvins being Christmas), a fan on Tumblr came up with the headcanon that Edith the Lunch Ladys birthday should be February 14; Valentines Day. So imagine that fans surprise when Dav Pilkey himself actually made it canon!
- Casting Gag: In the Mexican Spanish dub, the titular hero is voiced by Arturo Mercado Jr., who previously voiced a bald villain, Hammerhead, who also ends up naked. This time, he's the hero.
- Dub Name Change: This caused the film's release to be postponed in Spanish-speaking Latin America. In early trailers, the character names are left in English (except Captain Underpants). In the movie itself, the Spanish book translations are used after DreamWorks received complaints from fans.
- Dueling Movies: Captain Underpants was set to go up against Wonder Woman (2017), a "real" superhero movie, on the same day. Regardless, both films did well in terms of reception and several moviegoers have jokingly combined the two into "Captain Wonderpants."
- Milestone Celebration: The film is being released 20 years after the first book was published.
- No Budget: The film had a budget of $38 million, which is generally pretty low for an animated movie. It's especially low for a major studio like Dreamworks, making it their second cheapest film after The Curse of the Were-Rabbit. This is lampshaded by George and Harold when they mention showing the film's final battle would make it go overbudget, so they present it in Flip-O-Rama instead. It's also why most of the cast from the book are Adapted Out in favor of only five main speaking roles.
- The Other Darrin:
- None of the cast returned for The Epic Tales of Captain Underpants; George and Harold will be voiced by actual child actors.
- In Japan, since the dub of the TV series went first before the movie, the film replaced the entire dub cast, with the sole exception of Yasunori Matsumoto as the titular hero.
- Saved from Development Hell: The film has been here since 2012—the release date has been relocated a couple of times, Rob Letterman stepping down as director with David Soren replacing him, and DreamWorks' issues in the last few years probably haven't helped. Thankfully, it seems like they finally got the ball rolling because the first trailer came out on March 22nd, 2017. Letterman still serves as executive producer though. The film was finally released on June 2, 2017.
- So My Kids Can Watch: Kevin Hart has stated that his son being a fan of the book series is one of the factors that drew him into voicing for the film.
- What Could Have Been:
- A live-action movie was planned as early as 1997, right before the first book was published, and would have starred Chris Farley. The project was scrapped after Farley died.
- According to director David Soren, in an early draft of the film there was going to be a small scene that confirms the Fanon theory that Edith is an Alien.
- In an interview, David Soren mentioned that in an earlier draft of the film, there was going to be an homage to Magnolia during the scene where George and Harold are separated, and it was going to have all the main characters from Krupp, to Poopypants, to Melvin, to the gardener outside the school mowing the lawn, having a little refrain. They all sang about how they were feeling unsatisfied by their current situation, and lonely. Ultimately, the scene just didnt work with the flow of the film, and was cut.
- In one of the earliest drafts of the script, before David Soren took over as director, there was going to be a subplot about Harold starting to hang out with the cool kids, causing a rift between him and George. Thankfully, the filmmakers quickly realized that this subplot did not work at all (mainly due to it being extremely out of character for George and Harold), and it was cut.
- Early information about the movie had Dr. Diaper, the Big Bad of the first book, as a secondary antagonist.
Trivia / Captain Underpants: The First Epic Movie