As US Representative Joe Courtney watched the Oscar-nominated Lincoln, something didn't seem right to him.
He said he was shocked that the Academy Awards favourite, about President Abraham Lincoln's political struggle to abolish slavery, includes a scene in which two Connecticut congressmen vote against the 13th amendment to the Constitution, outlawing slavery.
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"'Wow. Connecticut voted against abolishing slavery?"' Courtney recalled hearing audience members ask.
"I obviously had the same reaction. It was really bugging me."
The film is already lining up to be one of the most error-filled movies of the year, with eagle-eyed viewers spotting almost 30 gaffes in the film, eclipsing the 26 errors in Bond blockbuster Skyfall.
Courtney said a cursory internet search confirmed his suspicions that the movie, directed by Steven Spielberg, was historically inaccurate.
He asked the Congressional Research Service to investigate, and it reported that all four Connecticut congressmen backed the amendment in a January 1865 vote.
A spokesman for Dreamworks Pictures, which produced Lincoln, did not immediately respond to an email seeking comment.
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Courtney praised the film's acting and cinematography but said artistic license does not permit it to inaccurately put Connecticut on the wrong side of history, particularly on an issue as powerful as slavery.
In a letter to Spielberg, the four-term Democratic congressman includes a tally of the 1865 vote by the state's congressional delegation and a passionate defence of the state's role in emancipating millions of blacks.
"How could congressmen from Connecticut - a state that supported President Lincoln and lost thousands of her sons fighting against slavery on the Union side of the Civil War - have been on the wrong side of history?" he said in his letter.
Courtney, who majored in history at Tufts University, asked that the movie, which stars Daniel Day-Lewis as Lincoln, be corrected before its release on DVD.
Other mistakes detailed on movie website IMDB.com include a vanishing cigarette, a torrential downpour which suddenly becomes a light drizzle, a scene featuring a bust of President Woodrow Wilson, who was only a child during the years in which the movie is set, bright daylight outside the White House at 5pm in November, and a disappearing American flag.
Lincoln, which leads the Oscars with 12 nominations, also stars Sally Field as Mary Todd Lincoln and Tommy Lee Jones as Thaddeus Stevens.
Lincoln opens in Australian cinemas on Thursday.