The film follows married couple Joanna (Keira Knightley) and Michael Reed (Sam Worthington), who are tempted by different forms of infidelity when they spend a night apart following a fight.

Joanna is emotionally drawn to her ex-boyfriend Alex Mann (Guillaume Canet) while Michael is physically attracted to his co-worker Laura Nunez (Eva Mendes).

The cast includes Griffin Dunne, Daniel Eric Gold, Anson Mount, Stephanie Romanov, Scott Adsit, Justine Cotsonas, and Chriselle Almeida.

Last Night was produced by Entertainment One in association with the Gaumont Film Company, and deals with questions about emotional and physical infidelity.

After persuading Knightley to break a year-long acting hiatus to participate in the film, Tadjedin cast the other roles with consideration for the actors' chemistry.

Miramax Films initially bought Last Night for a March 19, 2010 release, but it was delayed by the company's sale to Filmyard Holdings.

Joanna, a writer, and Michael Reed, a commercial real estate agent, are a married couple who share an apartment in New York City.

During a party with Michael's colleagues, Joanna notices him spending time with Laura Nunez, an attractive co-worker and wonders why he has not previously mentioned her.

[5][6] She completed the script roughly four and a half years prior to its release;[4] she developed the scenes out of sequence and wrote them with Microsoft Word.

[8] After a negative response from a Warner Bros. studio executive on the script's formatting, she realized Final Draft was the preferred software for screenwriters.

[9] Requesting seven million dollars for production, she had difficulty with financing the film,[7] and rejected a potential source for not understanding her "artistic vision".

[11] The Los Angeles Times partially attributed the difficulty in selling Last Night to a film studio to it being an adult drama, which it described as "endangered in Hollywood".

[12][13] Tadjedin likened Last Night to a slice of life story, a genre that she enjoyed in her childhood,[8] while Griffin Dunne identified it more as a "moral thriller" due to its focus on "a universal passage in a long-term relationship".

[19] During a 2018 interview with Peter Travers, Knightley cited Last Night as one of four films that meant the most to her; she enjoyed it for the collaboration with the cast and crew and its more naturalistic style of acting.

Tadjedin wanted the apartment's furniture to represent the characters' personalities and the state of their relationship because the film does not depict their histories.

He asked Tadjedin to remove a line referencing Michael and Joanna taking a flight home, saying, "Don't fuckin' have me explain why I'm from Australia".

Gaumont CEO Christophe Riandee said the company acquired the movie to prove its "determination to go forward with high-end English-speaking productions".

[36] Last Night was shown as the opener for the 2010 Rome Film Festival; the cast was unable to walk the red carpet for the movie due to protests by the Centoautori movement.

[37][38] The protest was held in response to Prime Minister Silvio Berlusconi's decision to stop tax exemptions for film productions and reduce funds for cultural events.

[6][7] The film had a limited release in ten US theaters on May 6, 2011,[3][42] where it received an R rating from the Motion Picture Association of America due to language and sexuality.

[5] The film was later packaged as part of the Echo Bridge Home Entertainment release Epic Romances with Anna Karenina (1948), As You Like It (1936), The Magic Sword (1962), and The Strange Love of Martha Ivers (1946).

[46][47][48] DVD Talk commended Tadjedin for not reducing the characters to "the monsters and angels normally created for cinematic takes on infidelity".

[49] While giving the film a positive review, Hot Press wrote that the effectiveness of its message was entirely "dependent on the viewer's own experiences".

[51] Last Night's plot and characters were described as lacking the "appetite for lunatic adventure" of Woody Allen's works,[16] or the emotional stakes of the 2009 film I Am Love.

[17] Filmmaker singled out Canet and Mendes for creating "original beats in their roles as possible paramours";[4] The Hollywood Reporter preferred their characters over Joanna and Michael.

[55] Mendes was praised as "particularly appealing" by Variety,[26] and for "resisting the urge to overdo (and overvamp) her role the way a lesser actress would" by DVD Talk.

DVD Talk cited his "dull and lifeless" acting as the film's main problem,[48] and Slant Magazine noted his "idea of underplaying is to go blank".

[46] Criticizing Worthington and Mendes as lacking chemistry, The Globe and Mail wrote that the pool scene was "ridiculously prim" and Laura was too "tired and remote" with Michael.

wanted the story to be "a little more even-handed towards Michael's character",[47] and The Boston Globe wished Tadjedin was more "generous with the rest of the cast as she is with Knightley".