Character mistake: Near the end, just before Derek and Danny depart at Danny's high school, Derek says to his brother "I saw a car cruising by the house last night when I pulled out of there with Seth." The car that was shown driving by their house the previous night was in a brief scene right after Derek and Danny took down all of their nazi posters, and before Derek took a shower. He had not just 'pulled out of there with Seth.' The last time he had seen Seth at this point in the movie was at Cameron's party where Seth had almost shot him.
Suggested correction: Just because Derek says to Danny that he saw a car driving by their house when he left with Seth and a black car drove by later in the movie doesn't mean that this is the car Derek was referring to. There are many possibilities to explain what Derek was referring to (perhaps he was paranoid and saw an ordinary car driving by that he thought was scoping their apartment out) but it doesn't mean that the black car is the one he was referring to when he warned Danny.
Character mistake: After the Congressman is killed, the killer dumps pills on the floor of the car. Then the car is then rolled into the river. At about 15:07 the news reporter mentions that the Congressman's heart pills were found in his lap. This would be impossible because the pills and bottle would float and the pills would dissolve in the water. (00:03:45 - 00:15:05)
Character mistake: Before the final attack in the village, we can see a wall with an advertising for Byrrh, an aperitif drink made from a blend of wines. The ad reads: "Byrrh, l'ami de l'estomach, " which basically means: "Byrrh, stomach's friend." In French, the correct spelling is "estomac." not "estomach." This is quite a big mistake since the ad and the building are three or four stories high.
Character mistake: After killing three of the 'new' soldiers, Todd says that there are seventeen left. He then kills about another thirty.
Character mistake: The newspaper headline quotes "parent's" death in a murder-suicide story. Should be "parents' deaths" as both have died. (We can forgive the newspaper not picking up on the fact they were killed by a government assassin).
Character mistake: While listening to the fixed record at the antique music instrument shop, Chris talks about 1800 instead of 1900. (00:30:45)
Character mistake: Jack accuses Marion of being a mug punter because she bets on the lottery, despite the odds of winning of "14.5 million to 1." The odds of winning the lottery are in fact 13,992,000 to 1 - not much better, but at least a precise figure.
Character mistake: The banner of the fundraiser event for the Gotham upper class says "Childrens Hospital", no apostrophe. (00:11:55)
Character mistake: The complaint that Robert Duvall is reading has a very obvious typographical error describing the decedents' conscious pain and suffering, 'concously'.
Character mistake: Just after the shootout between the robbers and the armored truck drivers at the dip in the road, the teacher that is with the robbers pumps the shotgun about 3 times, without firing a shot after they crossed the water. This would just waste a perfectly good cartridge, since they hadn't been shot yet.
Character mistake: At the meeting in Washington the general says nothing more frightening than a soldier with his M16A1, but they were using M16A2s.