Helen Mirren had to learn how to shoot a gun without blinking so as to look more like an experienced killer. (Blinking was one of the main reasons why the stars in the Matrix trilogy wore sunglasses to mask their involuntary reactions.)
John Malkovich read the first forty pages of the script and liked it. But he asked his agent why he was up for the role of Frank. He said Malkovich had been reading the wrong lines. He was up for Marvin's role instead.
The purse Victoria uses as a weapon was Helen Mirren's own purse. It was given to her as a gift from Giorgio Armani. Since it went so well with the dress she was wearing, and the purse was part of the script, she asked if she could use it. The producers said yes.
In Bulgaria, the film was distributed under the title BSP (Besni Strashni Pensii - which means Furious Frightful Pensioners). But BSP is also a mock title referring to the abbreviation of the Bulgarian Socialist Party (BSP). Its political color is red and its voters are mainly elder and retired people - just like the REDs.
Morgan Freeman's fake African dictator character is driven in a Mercedes 600 Pullman limousine, a favorite of world leaders including many developing-world/Communist-regime dictators such as Nicolae Ceausescu, Josip Broz-Tito, Fidel Castro, Pol Pot, Enver Hoxha, Leonid Brezhnev, Kim Il-Sung, Kim Jong-il, Idi Amin and Ferdinand Marcos.
In The Bourne Supremacy (2004), Karl Urban plays a Russian and Brian Cox plays an American. In this movie, this is reversed, with Cox playing a Russian and Urban playing an American. However, neither of these two actors hail from either of these countries, as Cox hails from Scotland, while Urban hails from New Zealand.
Victoria gets into Stanton's event with an invitation apparently bearing a pseudonym. An early draft of the script indicates that the line originally had the name as "Ms. Smith", but in the scene as shot, the woman at the entrance addresses her as "Ms. Brown". After the death of her husband, Britain's Queen Victoria was said to have become romantically involved with one of her servants, and slanderous rumors circulated that she had even secretly married him. His name was John Brown; thus, those spreading the rumor derided Victoria as "Mrs. Brown".
Bruce Willis and Julian McMahon have been engaged to model and actress Brooke Burns. McMahon and Burns were later married from 1999-2001, while Willis and Burns were engaged for part of 2003-2004, but were never married.
"Love's Savage Secret", the title of the "terrible", "awful" romance novel that Sarah is reading (and loving) seems to be a composite of two romantic fiction novels written by Joan Wilder (Kathleen Turner) in "Romancing the Stone": "Love's Wicked Kiss" and "The Savage Secret".
The first feature theatrical film based on a DC comics property not made by Warner Bros.. (Batman: The Movie (1966) (from 20th Century Fox) was a spin-off from a television series, and Superman (1948) (from Columbia Pictures) was a serial.)
When entering Frank's weapon container, Marvin picks up a submachine gun and comments that it's a "Swedish K". The weapon is a Kpist m/45, used by the Swedish military up until 2007. It was also made under license by Smith and Wesson with the designation "mod. 76". It was used by U.S. Special Forces due to its durability under harsh conditions, and it's therefore not unlikely that Marvin has used it as a service weapon.
John Malkovich tells Hellen Mirren's character in the kitchen shootout with the Secret Service, "I remember the Secret Service being a lot tougher", a nod to his villainous character in In the Line of Fire (1993).
The musical number being played by the stage band when Brian Cox and Helen Mirren dance (at Vice President Stanton's fund raising event) is the same number played by the country club band in the movie "Caddyshack" prior to Rodney Dangerfield tossing the band members some money.
Ivan Simonov is the Russian SVR "rezident", the Russian equivalent of the CIA station chief. It is extremely unlikely that he would be unknown to the Secret Service and current CIA agents, especially considering that he was known to both Frank Moses (CIA) and to Victoria (MI6) who was ordered to kill him. He would not have been allowed anywhere near the Vice President's fundraiser.
The trivia items below may give away important plot points.
Karl Urban nicked Bruce Willis with the cup he throws at him in their fight scene, because he threw it faster than Willis expected. You can see the slight look of surprise on Willis' face in the scene.
The CIA operative posing as a police officer is named Endercott. Former CIA agent Robert Baer, who served as a consultant for the film, was initially given the cover name Endacott when he became a CIA agent. (From his book, See No Evil)