Continuity mistake: When Eddie Murphy's assistant makes assumptions about why Jack isn't speaking, he throws his notepad down and has empty hands as Jack pushes him out of the office. When the angle changes, he has a notepad in his right hand.
Factual error: The movie changes between a basketball season and a playoff basketball game then to a baseball game being played in what looks like early summer...back to a team getting ready for the basketball playoffs. The two seasons don't overlap.
Character mistake: It's said in the movie a vice presidential candidate never gave a concession speech. Geraldine Ferraro did this in 1984.
Continuity mistake: The German and British airmen are looking at the Northern lights. From the rear the men are apart, but the front shots of them show them much closer to each other.
Continuity mistake: Throughout the film, John Travolta's hair changes back and forth and back and forth from being really really really short to just really short.
Revealing mistake: In the opening scene, Johnny and Hickey sit in the front seat of a car. Views out the side windows blur, there is a gray background behind Johnny instead of the rear window, and when Hickey holds the cross toward the windshield, the "outside" is all grayish-white. At one point, there is light on Johnny's right forehead, cutting diagonally downward (too linear to be the sun), and another time, there is light behind Hickey on his headrest. (00:00:31 - 00:03:30)
Continuity mistake: The position of Beth's truck facing her motel room (106 or 706?) changes during the time she is talking to Holly. Sometimes the truck is closer to the room next to hers (105 or 705) and to where Beth is standing. Also, the truck's front tires are different distances from the curb. (00:48:25)
Continuity mistake: Tom walks into Anthony's memory. Anthony is sitting by the pool next to a table with two glasses of beer, which are 1/3rd empty. A few minutes later the memory is replayed, but this time both beer glasses are mostly full. (00:49:50 - 00:58:35)
Continuity mistake: In the parking garage scene, when Lindsay initially parks the sign states "Reserved For Walter Deeds." When being towed his name on the sign disappears. (00:06:30 - 00:10:45)
Factual error: Close up, very detailed footage of a Cobra citizens band radio is used for the scenes where dispatch radio traffic is coming over the police radio. Police dispatch does not, nor has it ever, used the Citizen's Band radio service. (00:11:25)
Factual error: Kuklinski is looking at a newspaper which is dated January 3rd 1983, and the text reads that Roy DeMeo was found dead the previous day. In actuality, Roy DeMeo died on January 10th 1983. (01:22:55)
Plot hole: In this Australian time-travel fantasy, a college student discovers a one-way time portal that allows him to travel one day into the past each time he uses it. While he at first attempts to rescue his girlfriend from a traffic accident that occurred a day earlier, he eventually travels back 50 years (one day at a time) to save his young grandfather. However, in order to go back 50 years (one day at a time), he'd have to repeatedly climb through the portal over 18,000 times. Apparently, it's not an issue, because the movie just glosses right over it in less than a minute.