At the end of the movie, Marty Huggins reveals a giant scar running across his torso, an injury he received as a very young child; photos showing a teenage Marty Huggins in a swim suit do not show this scar.
In the first debate scene, when Marty and Cam first walk out onto the stage, the two podiums are the same height. However, after they shake hands and go to their respective podiums, Marty's is considerably higher than Cam's.
When Tim Wattley is talking to Cam after interrupting their family time and sending his kids to their room we see Mitzy walking down the hall away from them. However, in the very next shot she is right next to Marty again.
At the party where the election results were revealed, there is a flag on the table in front of Marty that goes from being flat to being slightly pushed over and back to flat again without ever being touched by Marty or his wife.
After stealing the police car, Cam weaves along the deserted road before losing control, spinning round and crashing into a cow. As he approached that spot there was no sign of a cow standing there and it could not have moved into that position in the split second that the camera moved away.
At the very beginning of the movie, an on-screen quote is attributed to H. Ross Perot ("War has rules. Mud wrestling has rules. Politics has no rules"), and refers to him as a 1988 Presidential candidate. Perot ran for President twice: first in 1992 and again in 1996, the year he made the comment used in the film. He did not run in 1988.
North Carolina does not have 14 Congressional districts.
While giving his acceptance speech Marty says the district will not be sold to China, Brazil, Nova Scotia or any other country. Nova Scotia is a province in Canada and in fact not a country, but is included here to demonstrate Marty's ignorance.
Just after Cam Brady (Will Ferrell) punches the baby's face, the different newscasts use actual footage of the punch from the film itself (slow motion, baby's perspective, different angles...) and not moving images from what a video-camera of the News would take.
At the end, when accepting the congressional office that Cam Brady has declined, Marty Huggins says that he is going to "...end Daylight Savings Time. I hate when it gets dark early." In fact, DST extends the daylight so that it does not get dark early, but later.
After Cam is arrested, a reporter approaches him and asks "You were charged with drunk driving. Is it true you blew a 1.4?" A BAC of 1.4 would almost surely be lethal; at the very least, Cam would surely have been hospitalized, not walking around talking with reporters. It's possible that the character simply misspoke, meaning instead to say 0.14 which is above the legal limit for driving in all states and a much more believable BAC value.
Marty shows Cam the scar incurred by the broken playground slide that first motivated Cam to get involved in politics by running for school president. Marty's father is rich and well-connected, which is why Marty was chosen to contest the election, so the school board should have been falling over itself to remove the slide themselves in order to head off any impending lawsuit from Mr. Huggins.