Continuity mistake: When Howard Payne is in the elevator, he hears Jack and Harry doing something from above, and he reaches for his bomb trigger. In slow motion when he's picking it up, it has two buttons on it, yet when Howard pushes one of the buttons, the device now has three. (00:13:00)
Continuity mistake: When Jack is chasing the bus on the freeway in the Jaguar, an overhead shot is shown of the bus with three cars around it, but in the next shot of the traffic, the road is full of traffic which is surrounding the bus, which is highlighted by Jack having to swerve around the cars.
Continuity mistake: When Dennis Hopper's shooting the shotgun through the lift roof, the number of holes doesn't match the number of blasts. He shoots once and a hole appears. We then see a close up of him and he shoots twice more, but when we cut to the ceiling after the third shot overall, there are only two holes in it. Doesn't seem likely he'd miss the roof at a range of 2 feet. (00:18:55)
Continuity mistake: Near the end of the film when Keanu Reeves and Dennis Hopper are wrestling on top of the subway, if you watch Keanu's left wrist you notice he is wearing a watch. Yet throughout the scene it is obvious that the stunt double has no watch, because in the extreme action scenes, there are no signs of it anywhere on his wrist.
Factual error: Harry is a LAPD SWAT team member. SWAT trains and trains and trains, then exercises and trains some more. Harry would not be investigating the case as shown when he asked to see the files for the last 10 years. If he was on desk duty for his injury, yes, he could be working the investigation. But soon after, he was on the entry team at Payne's house. That would have required more prep work by the SWAT team that Harry would have had to be doing instead of looking through the files.
Factual error: In the bus freeway gap jump, a second after driving off the freeway edge, the bus has fallen beneath that edge level of the freeway. It would be impossible for it to have regained altitude to be above the freeway on the other side. It would have hit at best halfway between the wheels of the bus, if at all.
Factual error: As long as gravity is a constant, there is no physical way that the bus (traveling at 68 mph) could possibly jump the level, 50-foot horizontal gap in the freeway. Even at triple or quadruple that speed, the bus would invariably drop vertically by as much as a meter, with catastrophic results.
Continuity mistake: When Jack handcuffs Ray to the metal handrail, Ray's right wrist has the double bars facing up and single bar facing down, but when Jack tells the passengers about the gap and then uncuffs Ray before the jump, the handcuff's single bar is facing up on his right wrist.
Continuity mistake: The 2 SWAT team members are not visible on the preceding truck between two shots. (01:12:55 - 01:13:32)