Factual error: Although you'd have to actually live in Boise to catch the myriad of differences from the movie town, the most glaring is that the movie Boise appears to be a lush rainforest, like Vancouver or Seattle. The real Boise is strictly desert, and you won't find those green interstate medians anywhere near here.
Factual error: While tracking Kevin Costner, Thomas Hayden Church reads a bio listing Costner's birthdate as Jan. 8, 1955. He then says Costner served as a medic in Vietnam. But Costner's character would've been too young for Vietnam. He would've only become eligible for military service at age 18, in Jan. 1973! That was the same month the U.S. ended the draft and began bringing home the troops. Even if he volunteered, it still would've been too late to serve in Vietnam.