Production notes

Davis had wanted to make an action film which focused on guns and was devoid of explosions. He conceived the film after seeing a scene from John Woo's film Hard Boiled (1992), in which Chow Yun-fat rescues newborn babies from gangsters while engaged in a gunfight. Davis felt that the scene could be expanded into a feature film, a "gun-like" version of Run Lola Run (1998). By 2000, Davis had begun writing the screenplay; when the script was finished, however, studios refused to get it made after the Columbine High School massacre happened, causing him to shelve the project and return to making low-budget independent films. During his subsequent years as an independent filmmaker, Davis started putting together an animatic of the script's action scenes using a Wacom tablet and the iMovie app. The animatic, which he made originally as a hobby, became his pitch animation in finding a producer for the project. He sent the script to Don Murphy, a producer he went to film school with at the USC School of Cinematic Arts, and Murphy as well as co-producers Susan Montford and Rick Benattar enjoyed it. Murphy, Montford and Benattar also saw the film's potential as a big-budget production, so they sent the animatic to major film studio New Line Cinema. New Line executives Jeff Katz and Cale Boyter liked it and they passed it on to Toby Emmerich, who greenlit the project at the behest of New Line founder Bob Shaye. Davis's first choice to play Smith was Clive Owen, who signed as the lead because the script impressed him. The role of Donna went to Monica Bellucci, who liked the script and the character: an independent woman who "does dangerous, dark dirty things in a playful way". The multilingual Bellucci dubbed herself in the film's French and Italian versions. Davis cast Paul Giamatti, who usually played "nice guy" roles, against type to avoid the stereotype of a physically imposing villain, and because he believed Giamatti could deliver the duality of the role. Shoot 'Em Up was produced on a budget of $39 million. Principal photography took place in Toronto and lasted fifty-five days, with Hong Kong's Peter Pau serving as cinematographer. Before filming, Owen and Giamatti were trained in firearms. Although he found the stunts physically demanding, Owen resolved to perform most of them himself. In the skydiving scene, he was aided by a Cirque du Soleil safety harness. Eighty firearms were used during production, and $70,000 of the film's budget was allocated for 6,000 squibs.

Rotten Tomatoes gives the film an approval rating of 67%, with an average rating of 6.15/10, based on reviews from 161 critics. The website's "Critics Consensus" for the film reads, "As preposterous and over-the-top as Shoot 'Em Up may be, its humor and non-stop action make for a very enjoyable film." On Metacritic it has a weighted average score of 49 out of 100, based on reviews from 23 critics, indicating "mixed or average reviews". Audiences polled by CinemaScore during its opening weekend gave the film an average grade of "B−" on a scale ranging from A+ to F. Peter Travers rated the film 3 out of 4 stars for Rolling Stone, calling it "eighty-two minutes of hardcore pow. [...] You'll be exhilarated – also exhausted." Roger Ebert for the Chicago Sun-Times scored the film 3⁠1/2⁠ out of 4 stars, comparing it favorably with Sin City as "the most audacious, implausible, cheerfully offensive, hyperactive action picture [he had] seen". Frank Scheck in The Hollywood Reporter called it a "ramped-up action movie on steroids" that "makes Hard Boiled look restrained". Ebert extended his praise toward the film's acting, calling Owen's character sympathetic and Giamatti's "surprisingly, teeth-gnashingly evil". Scheck complimented Owen's "low-rent James Bond" performance, and was delighted to see Giamatti cast against his usual "nerdy" on-screen persona. A. O. Scott gave the film a scathing review for The New York Times, calling it "a worthless piece of garbage" and that it was one of several "witless, soulless, heartless movies that mistake noise for bravura and tastelessness for wit". Stephen Hunter in The Washington Post said the film "is just gunfights strung together, without a whisper of coherence or meaning. The fights are staged so that they all look the same, and the principle is always the same: The gunman's multiple antagonists never hit, and he never misses." James Berardinelli gave the film a mixed review, saying that while it delivered gunfights as advertised, he complained that it "pretty much consists of shoot-outs and chases overtaking each other like waves rolling onto a beach, each more over-the-top than its predecessor". Berardinelli scored the film 2.5 out of 4 stars, writing that he "like[d] the audacity and its willingness to push the envelope beyond the limits of good taste. In the end, it's a little too long and uneven to recommend outright, but [he] won't deny having enjoyed aspects of what Davis is offering." In 2016, Shoot 'Em Up made the list of "25 great action films that are 90 minutes or under" compiled by Nick Horton of Den of Geek. Rotten Tomatoes ranked Shoot 'Em Up at No. 111 on its list of the "140 Essential Actions Movies To Watch".