Factual error: The geography around the VLA in New Mexico is actually relatively flat - in fact one of the reasons why the array complex is there is because the land is flat. The canyon in the film was actually Canyon de Chelly, in Arizona, more than 170 miles (270 km) away. But in the film, when Ellie goes to the canyon, the radio antennas seem to be right there, insinuating that the canyon is part of the VLA's magical desert scenery.
Factual error: David Egan's obituary says he died on 'Wednesday July 5th 1997'. In 1997, July 5th was a Saturday. (00:45:30)
Factual error: The movie theater ticker says it's Monday, April 12th, 1997 - but the 12th was on a Saturday. (00:00:20)
Factual error: The Portuguese slave ship Tecora was one of the most notorious of the illegal slave ships, but no slaves were thrown overboard in mid-ocean as shown in the film - at least on the trip in question. The Portuguese were pros at the slave trade and had plenty of food on board to feed their "cargo" between Sierra Leone and Cuba. The only time a slave would be thrown overboard in mid-ocean was if his/her health posed a serious risk to the crew and "cargo". (Slaves were too valuable to just throw away for the price of their food.) Historically, though, there were instances where whole cargoes of slaves were tossed overboard. The British Royal Navy zealously patrolled the waters off West Africa to try to shut down the slave trade. If a British ship was sighted, the slavers sometimes tossed slaves overboard to destroy the evidence and prevent the seizure of the ship.
Factual error: In the scene where Lt. Exley arrives at the Night Owl after the murder, the patrol officer is wearing a Safariland velcro-fastened handcuff case on his left hip. That style of rounded cuff case was not introduced until the early to mid 70s.
Factual error: When Wesley Snipes, Diane Lane and Dennis Miller are climbing through the sewer system to get to the White House, Lane looks up and says that they must be under the National Mall because there's Pennsylvania Avenue. That is incorrect. The National Mall is located behind the White House. Pennsylvania Avenue is the street in front. They do not intersect.
Factual error: When D.J. is attacked by Dr. Weir, he is grabbed by the throat and is squeezed until his windpipe is broken, shown by the way he was breathing (or struggling to). When Weir seizes him again and throws him against a support beam, he screams in a way impossible for someone who just had his windpipe crushed.
Suggested correction: Dr. Weir doesn't crush DJ's throat at all. The noises he makes are simply choking noises because he is being picked up by his throat, there isn't even anything in the scene to imply his throat is being crushed, which in reality requires considerably more effort than most people believe.
Factual error: During the scene where Charlie's thug, Lo, is in the street with the homeless man and his "busket", Lo gets angry at him, pulls his Glock out and rakes the slide to chamber a round. However, in the next shots of Lo we see his Glock with the slide still back even though it should have returned to the closed position.