Continuity mistake: Near the end of the film, as Willis is about to shoot the First Lady, we see a close up of him wearing sunglasses (part of his cop disguise) and looking through his binoculars. We then switch to the binocular view of the podium, but the shot is not given a darkened tint - it looks as if he is looking through the binoculars without the sunglasses. When we switch back to the first view of his face, however, the sunglasses are back in place.
Factual error: On the ferry boat ride, which should have been from Canada to the United States, they were aboard a North Carolina ferry... The North Carolina flag was flapping in the wind next to the US flag. There was a closeup, and you could even see the name of the boat, which is named after a North Carolina Governor, and home ported in Moorhead City, North Carolina.
Continuity mistake: During the briefing on the hood of the car, after the regatta, both Mulqueen and McMurphy change positions at the cut from wide to closeup. Mulqueen is at the side of the car in the wide then in front in the close up. McMurphy is about a foot behind Preston in the wide to right beside him in the closeup then back again. Also Koslova lights her cigarette twice during the scene.