The original plates where filmed in Toronto, so Lindahl and team spent a week in New York taking thousands of panoramic still photographs of the skyline, which were later stitched together at high-resolution to create cyclorama backgrounds to composite into the shots. The panoramas were also used as 2.5D projections to create parallax. A projected matte painting was used for the sky and additional elements such as cars and road furniture were all composited together with the greenscreen stuntman. For the jump shot, the stuntman was lowered down on a wire, while the camera jibbed up to create the sense that he was falling. In post, the performer's legs were replaced in CG, as they weren't moving as required. Later Kick Ass appears to crash land on a taxi at street level, for this the greenscreen performance was re-timed, CG buildings placed in the background and the crowds were also shot on greenscreen to avoid any accidents with glass on impact.

Double Negative also set up the look development for the views from gangster Frank D'Amico's apartment, which was eventually outsourced to LipSync to match to when the shot count rose for the sequences.

Dneg digitally placed the apartment on top of a building that had been shot with second unit and helicopter unit photography in Toronto; however, when the designs for the apartment came back from the art department it was much bigger, so the whole building had to be replaced in CG. In Toronto, Dneg captured full survey and photographic reference of the building for modeling in Maya and to allow the changes Vaughn required, including doubling the width of the building and adding Frank's penthouse apartment on top.

Matte paintings were composited onto windows by LipSync to show New York skyscrapers at different times of day and night.

"The idea behind Frank's apartment is a '30s or '40s high rise and new, bigger shapes had been built around it so whenever you looked through Frank's window there are more modern buildings around it, and this was achieved by our week-long stills shoot in New York," Lindahl recounts. "We took thousands and thousands of shots and took the best bits and stitched them together and created a cyclorama of various locations that Matthew liked. We spend a lot of time in Frank's apartment, from early morning to bright sunlight to dusk to dawn and middle of night, so all of these locations had to be captured at different times of day.

"There's quite an interesting bit about the exterior of the cityscape out of Frank's apartment that we had to deal with. Basically, the end sequence starts with Hit Girl entering Frank's apartment very early in the morning and the whole fight sequence takes place up there and the sunrise is starting and when they finally take off on their jet pack the sun is up. The DP, Ben Davis, wanted the magic hour look throughout this whole sequence. So Ben changed the lighting for every setup to reflect this, so we had to make sure that we had the background material to reflect this as well, which is why it was important to take stills at different times of day at high exposure range to be able to grade a set of stills [accordingly].

LipSync, which also worked on Stardust, completed 305 shots overall and composited matte paintings onto the windows showing New York skyscrapers at different times of day and night, and added animated elements such as cloud textures, flags moving in the wind and lights switching on and off to bring the exterior to life.

Lindahl provided various 270° digital matte painting cycloramas and a CG model of the apartment, which established the layout and correct perspectives as the action moved around each room. LipSync rendered out the correct view of the DMP via Maya and RenderMan and applied further adjustments such as sky and building replacements, animated traffic at street level, day for night relighting and grading in comp to marry the live-action interior with the rendered exterior. The action-packed finale takes place in Frank’s apartment, and the vfx team added muzzle flashes, wounds and blood spurts to enhance the comic book violence.