Continuity mistake: In the scene when Halley just left from her counselor's office, Macon was going to go after her but the counselor stopped him. Then he was doing something with his hands and he had a pen. In the next shot, he sort of taps the wall, and the pen is gone.
Continuity mistake: After they have sex for the first time, Adam and Evelyn are on the floor and she tells him to smile into the camera that was filming them making love. The camera however, is pointed right at them on the floor, not on the bed where the scene started and they had the actual sex. (00:32:20)
Factual error: In the final gunfight, we see a close-up of Charley fanning the hammer and rapid-firing his six shot Colt Single Action Army nine times in a row. [Kostner has stated in interviews that this occurs because a short scene of him switching revolvers (he had a second revolver in his belt) was left on the cutting room floor. Still a mistake, but there's the reason.]
Continuity mistake: After May and Darren make love he gets up and puts his pants on. We see him closing his belt, but in the next shot where his pants are visible the belt is open again. (01:09:40)
Other mistake: When "the killer" is pumping gas, if you count the clicks associated with a liter going into the tank, they equal a total of 33 liters of gas, not 27 which is what the pump stops on.
Continuity mistake: At one point about halfway through the movie, Jerry Falk sits down in his apartment to translate his thoughts onto his laptop, sort of a mini diary, and the closeup shot of the notebook monitor shows he has typed up over 3 lines worth of text (at 18-point font size setting, no less). Then the next wider shot that includes the laptop screen shows he hasn't finished even the third line; not only that, the text is now in more typical (smaller) font size.
Revealing mistake: The movie takes place over the course of several years, as large segments of time pass between scenes of Will and Jane meeting at the airport, and other encounters. Thus, it is rather jarring to notice that their twelve year old children, Ben and Claire, don't appear to age at all. Young adolescents usually change in appearance quite drastically as they mature.
Revealing mistake: Although the film is supposed to take place in New England, and there are constant references to how "Americans" do things, all of the license plates are from British Columbia.
Factual error: Near the end of the movie a Greyhound bus is shown. The route through Taos to El Paso is served by T.N.M. & O. T.N.M. & O. was purchased by Greyhound many years ago. However, the buses were marked with T.N.M. & O. as of a couple years ago when I rode the bus from Taos to Albuquerque. As of today greyhound.com still shows it as being served by T.N.M. & O., not Greyhound.
Factual error: During the film, there are extracts of two songs - 'The Spy' and 'Maggie McGill' - from the Doors' fifth album, Morrison Hotel. Great songs, however the film is set in 1968 and Morrison Hotel was not released until 1970.
Other mistake: Daniel was number six that she dated and treated as a boyfriend before Peter, so In reality Peter was number seven.
Continuity mistake: When Daniel Craig stays out late and, finally, comes home to his wife, he takes his tie off, but doesn't undo the top button of his shirt, but that button, suddenly, is undone.
Revealing mistake: When Rolfe is walking down the hallway to Sally's apartment, there is an orb where the hallway is lighter colored and his legs seem to jump and undulate due to the special effect used to hide the fact that the actor is actually full-sized, walking on his knees.