Continuity mistake: In the elevator scene, when Jack is on top of the elevator, Payne sends the elevator to floor 46 from floor 28, but a second later when Jack looks up at the camera, if you look very closely, you can see he is on floor 15...16...17..., but he's supposed to go up from 28 to 46. (00:02:10 - 00:05:15)
Visible crew/equipment: When the guard walks past the pillars at the start, on the first pillar you can see a shadow made by the film crew. (00:03:00)
Continuity mistake: At the very start of the movie, in the basement, you see a security officer walk past some numbered steel pillars, he walks past the pillars numbered "15" twice. Fixed in the Blu-Ray. (00:03:35)
Revealing mistake: The whole structure surrounding the elevator appears shiny and spotless, with the wires lacking a single spot of grease, revealing it's a set. (00:04:25)
Continuity mistake: At the beginning, when the employees are getting into the elevator, there is a close view of the man at the front pushing the button with his finger, but when it cuts to a wider shot, he is taking his thumb away from the button, instead of his finger. (00:04:35)
Factual error: When the terrorist's first target, the elevator, first has its cables blown, it goes into free-fall for about 7 floors before the brakes kick in. That is about a 100 foot free fall, and not one person even falls down afterward. Are we to believe that around 5 seconds of negative G does not even result in a single person ending up on their rear? (00:05:00)
Revealing mistake: When Harry and Jack arrive at the building at the start in the police car, you can see the tire skidmarks on the road from previous takes. (00:05:05)
Continuity mistake: When Keanu and Jeff are on their way to the building at the start of the film, their car flies over a hill and lands back on the road. The right hand front wheel takes a really nasty knock as it lands and looks ready to come off, and yet in the next shot they arrive safely with no apparent difficulty driving the car. (00:06:00)
Revealing mistake: In the shot where Jack and Harry are descending a ladder to the stranded elevator, we get a good look at the elevator shaft and its surroundings. Upon closer inspection you'll notice how the lowermost section of the shaft is actually a mural - given away by the shadows cast upon it. (00:09:20)
Continuity mistake: When they run onto the roof near the start, there's another trooper behind Harry running onto the roof (only visible in widescreen - in 4:3 it looks like a weird reflection). In the following shot of Keanu Reeves you can see the reflections of Harry and the other guy on the plastic covering the scaffolding. We're led to believe that Harry and Jack should be the only ones up there, as everyone else has a job to do. Aside from those two shots, this third trooper disappears once they start hooking the crane up. (00:11:30)
Visible crew/equipment: Aside from the mysterious other trooper(s) reflected in the tarpaulin on the roof near the start, as Keanu Reeves runs past it, you can see the clear silhouette and red light of a cameraman filming the scene. (00:11:30)
Continuity mistake: When Jack and Harry are on the top of the building at the start, Jack climbs up a ladder and proceeds to walk along to the crane. In one shot he moves the big gun round to his back, and in the following shot the big gun is still in front of him. (00:11:55)
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)
Factual error: If you look at the loop Keanu hooks the crane onto on top of the lift you can see that it and its bracket have been recently welded on (by the black residue it leaves), obviously because the lift itself didn't have such a loop. Even if such a feature existed, it wouldn't be simply spot welded on the top as this one is, it would need to be part of the lift's structure if it were to serve any purpose in supporting it in an emergency. (00:13:05)
Factual error: When Payne blows the safety catch on the elevator it shows a shot of the floor level indicator going down from 29 to 25 in about 3 seconds. The camera cuts to inside for 5 seconds then the cable stopping the lift. This has taken approximately 8-10 seconds in total, but they are only on the 22 floor now. By the rate of which they were falling they should be on at least the 13th floor. Not taking into account that it would be accelerating as it goes down. (00:13:45)
Continuity mistake: When the elevator free falls and the floor opens, all the shots from below, with or without the woman falling through the hole, show the elevator is empty. (00:13:50 - 00:13:55)
Continuity mistake: At the beginning of the movie after Jack has hooked up the crane from outside to the lift, there is a shot of the crane outside, and the line going through the vent. If you look closely there is a pipe in front of the vent, yet when the crane goes through the vent, the pipe has vanished. (00:14:20)
Continuity mistake: When the crane is torn out of the floor and flies towards the ventilation window, from a shot behind, the holes on the base (where the screws used to be) are gone. (00:14:30)
Audio problem: When Jack and Harry are running down the stairs to get to the elevator Harry radios his lieutenant and says "Mac we need more help up here now", but his mouth does not appear to be saying these words when it is visible. (00:14:40)
Continuity mistake: When the crane breaks free from its bolts and starts flying towards some ventilation windows, it obliterates the upper pair. However in the next view from within an air duct, both of these windows just swing open freely as the crane busts through, and yet they barely appear to have suffered a scratch or bend in the process. (00:15:00)