Some of Red Mist/The Motherfucker's nastier moments from the comic, including murdering children and rape were omitted from the film. Christopher Mintz-Plasse 's reaction to this was literally, "Oh, thank God".
The lines "Try to have fun, otherwise, what's the point?" and "Yeah, there's a dog on your balls!" were both improvised by Jim Carrey.
Evan Peters was unable to reprise his role as Todd Haynes because of scheduling conflicts with American Horror Story (2011). Similarly, Lyndsy Fonseca was only available for a brief cameo as Katie Deauxma due to scheduling conflicts with Nikita (2010).
Mark Millar was actually delighted by Jim Carrey's disapproval of the film's violence. In his own words, Millar described it as "like saying 'this porno has too much nudity.'"
Jim Carrey bought his own props to look like the comic book version of Colonel Stars and Stripes.
Colonel Stars and Stripes is a combination of two characters from the comics: Colonel Stars and Lieutenant Stripes (they're brothers).
According to Chloë Grace Moretz, a sequel to 'Kick-Ass 2' would be unlikely because it was as she called it "one of the number one pirated movies of the year", leading to disappointing box-office returns. Slashfilm debunked her claim pointing to the fact that 'Kick-Ass 2' wasn't even among the top ten most pirated films of 2013 and instead attributed the film's poor box-office receipts to the general consensus that the sequel "never came close to the energy and smarts of the first movie", as put by Germain Lussier at the time of the film's release. However, Matthew Vaughn, director of the first movie, has indicated that he still has plans for a Hit-Girl prequel, and a third Kick-Ass movie.
The posters seen in Dave's room, "American Jesus" and "Superior", are two graphic novels written by "Kick-Ass" author Mark Millar.
Two characters from Kick Ass (2010) were carried on to Kick Ass 2 (2013) but were cast as different actors. Todd, originally played by Evan Peters, is now played by Augustus Prew. Marcus, originally played by Omari Hardwick, is now played by Morris Chestnut.
The Motherfucker's lair was actually a warehouse at Pinewood studios. Following completion of filming, it was demolished in order to build a new soundstage.
In the comic for the first Kick-Ass, Dave states that he likes the television series Scrubs (2001). In this film, Dr. Gravity is played by Donald Faison, who also plays Turk in Scrubs.
Lindy Booth (Night-Bitch) previously worked with director Jeff Wadlow on his first film, Cry Wolf (2005).
In the movie the character Insect Man says he became a super hero because he was teased and bullied in school because he is gay. He says that today he is very proud of who he is which is why he does not wear a mask or make any attempt to conceal his identity. In the comic the character is dramatically different. At a meeting of the members of Justice Forever Insect Man claims to be a police officer who is tired of playing by the rules and wants to brutalize criminals which is why he chose to become a super hero. Also he does wear a mask and makes an effort to conceal his identity.
In one scene, where Dave and Mindy are talking, Dave is wearing a shirt that says "I Hate Reboots". That same year, Chloë Grace Moretz starred in a remake of Carrie (1976).
The statue of a child wearing an Army helmet, and holding a grenade in the villain's lair, is titled "Boy Soldier" by British artist Schoony.
In the comic, it is implied that the character of Colonel Stars (Colonel Stars and Stripes in the movie) had terminal cancer and may not have had long to live which explained why he renounced his former life as a mob enforcer, became a Born Again Christian and became a Superhero. However this is never confirmed. The movie omits this point.
Many of the characters talk about Batman. Jim Carrey starred in Batman Forever (1995).
The Region 1 DVD and Region A Blu-ray, from Universal Pictures, include an Audio Descriptive Track.