Factual error: We are told at some point that Nicole Kidman has dual nationality because she was born in the US. In the final scene, when she is talking with Sean Penn about her future steps, she says she has been deported and given one day to leave the country. She was a US citizen, so it is impossible that she would be "deported".
Plot hole: Toward the end of the movie, it is revealed that Silvia spent the night in the secure room where the Matabo President was taken after the assassination attempt so that she could be alone with him and threaten to kill him. With the U.N. and Secret Service on alert for an assassination attempt, wouldn't they have swept the secure room right before the Matabo President arrived that day? In addition, Silvia would have had to use her access card to get in that area of the building, so there would be a record of her being in the building but not at her station. Wouldn't that raise some suspicion long before Tobin figures it out?
Deliberate mistake: When the Matoban delegation arrives at the UN, it shows the motorcade entering the circle in front of the UN Secretariat building and stopping at the revolving doors right at the front the staff entrance. Diplomats' motorcades always continue on to the delegates' entrance under a protective tent in front of the GA building so as to allow VIPs to alight from their vehicles to prevent potential snipers from having a view of them. The very next shot of the ambassador shows him riding the escalator, which is at the delegates' entrance, going up to the General Assembly building. This would not have been possible unless they made him walk about 300 meters outside in broad daylight. No chance of that seeing he was already being protested on 2nd avenue all the way from the Queensboro bridge. Obvious reason for this error: The shot of the delegation getting out of the cars looks far better in the open right in front of the UN secretariat building rather than inside a protective tent.
Plot hole: After the photographer is found dead in the bathtub, Sean Penn grabs the letter the photographer wrote to Nicole Kidman. He reads it to her in the park in English. Why would the photographer write the letter in English? He almost always speaks to Nicole in French, and if he wanted to keep the letter private he would have certainly written it in French.
Visible crew/equipment: When they show the sea (or ocean), a small part of the camera is seen at the side of the screen. (Visible on widescreen DVD.)
Plot hole: There is simply no way that the United Nations would let Zumanie set foot into that building with an assassin still at large. Despite the movie's emphasis on his absolute need to be there that day or whatever, once a New York City bus blows up and the attack has ties to a soon-to-be visiting African leader's possible assassination, the U.N. should've been a ghost town.
Continuity mistake: Towards the end of the movie, in the scene when Kidman is telling Penn that she "is going home", throughout the scene her hair changes from staying behind her ear when the camera is behind her, to blowing behind her ear when the camera is on her face.
Other mistake: The photo of Silvia and her brother, walking on the road with guns in Africa, looks like a composite and is obviously a fake made up for the movie. The images of those two look flatter and have slightly different contrast compared to people in the rest of the photo; separate photos of them have been cut and pasted onto the road photo.
Plot hole: At the end of the movie, Philippe tells Sylvia in his letter that Simon, her brother, was shot by a young boy. Philippe would not know this information because he was not in the soccer arena. Although he heard gunshots, there is no way that he knew that he was shot by a young boy.
Deliberate mistake: In the shot where peoples' bags are being checked in the two Xray machines as President Zuwanie is arriving, you can see that both monitors are showing the exact same bag's contents. Also, although you can see one of the machines' Xray-active light turning on, the image on the monitor does not change. (01:40:35)
Plot hole: When the Security chief is discussing the plan with the assassin, they are overheard by Nicole Kidman over the General Assembly microphones through a pair of headsets. Normally all this equipment is turned off when not in use to protect the system. The sound man had time to turn it off before he left even with an evacuation in progress. There was no way that the two were intending to be overheard either, as there was no way that either of them knew if, or when, anyone would be in the booth.