Contest Winner Cameo: Kind of, but going a bit beyond it: Dave Lizewski, winner of a charity auction and contest to name the main character, named him after himself.
Overtook The Movie: The film and book were written at the same time, with both influencing the other and things being changed to keep them consistent.
Recursive Adaptation: In regards to the tone at least. Kickass part 1 was unrelentingly cynical, with the main character not getting much of a happy ending. Then the movie adaptation came out which was a fair amount more idealistic and had a happier ending for the lead character. Then by the time of part 3 of the comic, things start going right for the main character and he eventually gets his happy ending after much suffering.
When I was 15, my best friends and I were reading Frank Miller comics, like Batman: Year One. (...) We were so into it, we should have been studying for exams at the time. We wanted to become superheroes like Batman. It was pathetic. We were five years too old really to be doing this. The story was really about what would have happened if we hadn't come to our senses and actually gone out and done this.
John Romita Jr. said that he decided to add personal touches of his own to the series when he found out that the series had a personal connection to Millar. Romita designed the neighborhood, schoolyard, setting, and clothes in a manner that evoked his neighborhood in Queens, New York City; most of the time the series is set in Romita's neighborhood.
Actor-Inspired Element: Nicolas Cage came up with his character's "disguise": that Damon Macready would have a mustache, while "Big Daddy" would have an even larger mustache via adhesive extensions.
California Doubling: Despite being set in New York, the film was shot in England and Canada.
Channel Hop: Matthew Vaughn initially went to Sony, which distributed Layer Cake, but he rejected calls to tone down the violence. Other studios expressed interest but wanted to make the characters older. In particular studios wanted to change Hit-Girl's character into an adult.
Creative Differences: Production Designer Martin Childs was fired by Matthew Vaughn, early in the production, because they were "not on the same wavelength". Russell De Rozario was hired as his replacement five days before shooting started.
Mark Millar has said that the movie is superior to the comic book. He had originally devised the comic story as a movie pitch.
John Romita, Jr. stated that Big Daddy's story in the film "works better stopping short ... You love him better in the film". Millar stated that the revelation about Big Daddy's background would not have worked in the film adaptation, and "would have ruined the movie."
The Danza: Christopher Mintz-Plasse plays Chris D'Amico.
Dawson Casting: Christopher Mintz-Plasse (Red Mist) and Lyndsy Fonseca (Katie), as well as several other actors, are in their early 20's yet play teenage characters. Downplayed with Kick-Ass himself; Aaron Johnson was 19 when the film was released.
Development Hell: The sequel. It was initially announced to be made for a 2012/2013 release but is on hold due to Aaron Johnson taking time off acting to be with his daughter and Matthew Vaughn directing other projects. It was released in 2013 and directed by Jeff Wadlow (with Vaughn's blessing/supervision).
Dueling Works: With Defendor and Super. Kick Ass won easily, being the most critically acclaimed and financially successful. (76% on Rotten Tomatoes for Kick Ass, 74% for Defendor, 49% for Super; and Kick Ass making $96 million worldwide, with Defendor and Super not even making $1 million worldwide combined) Worth noting that all three were developed independently of each other; and Mark Millar supported Super by showing it at his comic festival, Kapow!, in London.
It seems that before ending up in Lionsgate, the producers of the movie tried several other studios who all had the same condition: "We'll take it, if you drop Hit-Girl or make her 19." Thankfully, they didn't.
The entire reason Red Mist survives the end of Kick-Ass 2 is because when Mark Millar told Jeff Wadlow (director and writer of the second movie) of the character's death, he argued that they couldn't kill the character off as he's one of the series' staple characters & they couldn't really do Kick-Ass 3 without the character.
Funny Character, Boring Actor: In the film, Chloë Grace Moretz's character dropped the C-bomb before slaughtering a bunch of bad guys in a scene that she filmed when she was twelve, and which Moral Guardians often pointed to in order to whip up outrage against the film. Off set? She couldn't even bring herself to say the title out loud, calling it "the film" in interviews and "Kick-Butt" in private.
No Stunt Double: Matthew Vaughn said that Chloe Moretz did "an amazing amount" of her own stunts, training for a month with a Toronto circus school before she even got on set, and then training some more. Behind-the-scenes video tends to confirm this.
The Red Stapler: Hit Girl's dual Benchmade 42 butterfly knives. Between the popularity of Hit-Girl and her specific mention of the Benchmade 42 balisong/butterfly knife, the fact that Benchmade had stopped producing the model a few years prior, and the fact it was already a somewhat sought-after knife in collecting communities, demand for the knives far exceeded the supply. Prices for an as-new model nearly tripled what they had been months earlier. Because of this spike in demand, Benchmade retooled and produced a very small number of new limited edition BM42s, which sold for over $1,000 each.
tends to confirm this.