There were talks between the studio and the Salamanca Film Commision to shoot the entire film in the Spanish city, but it was considered inviable after the local authorities refused to close the Plaza Mayor during nearly 3 months. As a result, the production was moved to the Mexican cities of Cuernavaca and Puebla. Only the scenes filmed from the air were shot in the real Salamanca.
As the shooting was moved to Mexico, the production design department was forced to build a replica of the Plaza Mayor of Salamanca in Mexico. The replica is slightly smaller and simpler than the original.
The release date was originally planned to be in October 2007 but was delayed till February 2008 for unknown reasons.
Salamanca or Salamangka is a common word for "trick" or "sleight of hand" in Filipino. This location may have been chosen to "poke fun at" the many plot twists in the story. The word and its meaning most likely originated from Spain since the Phiilippines had served as a Spanish colony since Magellan's arrival in 1521. The word is only used as a place in most modern Spanish dictionaries.
Sigourney Weaver's second film about an Executive level cover-up between a stand-in and "real" president, whose life is in peril. The first being Dave (1993)._
According to the original script, the movie would take place in Madrid, but it was changed because the producers wanted a more "exotic" location. This is given away in some scenes, like when the secret service guy says they can't locate a single person among "5 or 6 million" (Madrid's population, not the much smaller Salamanca's), or when the cop enters a Muslim neighborhood during the foot chase scene (again, those exist in Madrid, not Salamanca).
TV Executive Rex Brooks (Sigourney Weaver) was originally written as a male. Director Pete Travis changed it to a woman because he felt the movie lacked a strong female character.
In the original script, the tourist was a Russian named Lewicki. When Forest Whitaker auditioned for a different role, Pete Travis was so impressed that he rewrote the tourist as an American and offered the role to him.