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.

This is Jeff Wadlow's first R-rated film.

Many of the characters talk about Batman. Jim Carrey starred in Batman Forever (1995).

Aaron Taylor-Johnson and Daniel Kaluuya previously appeared in Chatroom (2010).

The Region 1 DVD and Region A Blu-ray, from Universal Pictures, include an Audio Descriptive Track.

Included in "The A to Z of Superhero Movies: From Abar to ZsaZsa via the MCU", written by Rob Hill.

Creators Mark Millar and John Romita, Jr. have cameos as superheroes in the climactic battle between the superheroes and the supervillains.

Jim Carrey only has 7 minutes and 45 seconds of screentime.

In a deleted scene of the film, just before the climactic fight starts, Eisenhower runs in and bites the Mother F***er's crotch.

In the wake of the Newtown Elementary School shooting in 2012, Jim Carrey refused to take part in any promotion campaigns for this film, because he felt he could no longer support its violent content. Carrey is known for his personal distaste for guns and gun violence, not unlike his character in the movie (the only gun the Colonel handles in the film is unloaded).

When Mother Russia is destroying the police cars, Korobeiniki, a traditional Russian song which is widely known for appearing as a theme music to "Tetris", is playing.

When Mindy is going out on her date, she tells Marcus not to worry because she can "kill a man with his own finger". Later, in the final battle scene, Hit-Girl kills Black Death with his own finger.

Mother Russia has a tattoo on her left arm, which you can see right after the scene when Motherfucker tried to rape Night Bitch. Translating from Russian it says 'Don't fear, don't beg, don't believe'.

During the Flashback during the funeral, you can see the name Mark Millar on top of the poster. Mark Millar is the author of the Kick-Ass comics.

When The Motherfucker is destroying Colonel Stars and Stripes' lair, a rarely used 49 star flag can be seen. After he says "Let's trash this place!" you get a clear shot of it. The flag was used for less than a year after Alaska joined the Union in 1959.