Visible crew/equipment: During one of the railroad men's eyewitness accounts of what he heard at the time of the assassination, for only a second on the extreme far right of the screen during the obviously re-enacted footage of the fateful motorcade, you can see just ahead and on the driver's side of the Lincoln limosuine the white sedan lead car; however, you can see it is mounted with what appears to be a boom microphone and other equipment and crew members in the car - one has a headset on. (01:06:25)
Factual error: In one of the scenes where Costner is interviewing the witnesses in Dallas. One old guy says he was standing on the overpass and saw a man running back toward the railroad area behind the Grassy Knoll. There is then a shot, back in time, to the day of the assassination, where the shot of the man running is re-enacted. You can see him running by a Ford Mustang. The first Ford Mustangs were not released until April 1964. The man was running by it on November 22, 1963.
Continuity mistake: In the scene where Jim Garrison is interviewing David Ferrie in his office, while Ferrie is being escorted out of Jim's office, the camera goes to the T.V. Notice the light in the background behind the T.V. The light in the background is pitch black, and then in an instant, the light comes on as if someone turned on a light. (00:04:05)
Continuity mistake: During the scene where Garrison and Mr. X are sitting on the bench, Garrison turns his head slowly towards Mr. X's direction. At the next shot he's still, and his head is back to where it was.
Continuity mistake: After hearing about the death of JFK in a New Orleans bar, Guy Bannister & Jack Martin walk all the way back to Bannister's office in a pouring rain. As we see the two go inside the office building into Bannister's personal office, their overcoats and hats are completely dry. (00:12:31)
Continuity mistake: When Jim Garrison goes to Angola Prison to interview Willy O'Keefe, Willy tells of a time before the assassination of JFK where he was alone with David Ferrie, Lee Harvey Oswald, Clay Shaw, and two Cubans. When we see the flashback, there are a total of six Cubans in the room, not two. (00:50:05)
Factual error: About two thirds into the film, in a flashback scene, a military-uniformed man is at an airport in New Zealand. In the background the silhouette of a 737-300 is seen landing. The film is set in the early 1960s, but the 737 did not enter service until 1967, and the -300 series not until the mid 1980s.
Factual error: The day of the assassination, Guy Bannister, thrilled with Kennedy's death, sits in a bar with Jack toasting "Camelot in smithereens." The Kennedy administration did not come to be known as Camelot until Jackie Kennedy mentioned her husband's fondness for the musical in interviews several weeks after the assassination.
Continuity mistake: At one point during the meeting between Kevin Costner and John Candy, Candy bolts out of his chair and the sunglasses he was wearing fall off. In the next cut Candy is wearing them again without having picked them up. [This scene is edited from a longer scene (that is included on Disc 2 of the JFK "Oliver Stone Collection" DVD). In that sequence, Candy sits down and puts his sunglasses back on. Still a mistake, though, but there's why.]