Revealing mistake: When the bus jumps the gap and comes into land, you can see there are no passengers, not even dummies.
Continuity mistake: In the cafe, Jack shouts to Bob "Have a good one" and holds his arm out with his coffee in his hand. When the shot changes and Jack is turning back to the counter, his coffee has swapped hands. (00:26:20)
Audio problem: Right before they get off on the first exit to city streets, there's a shot of one of the passengers (Helen) who makes a distressed moaning noise. Her moan has an odd noticeable echo that is very out of place.
Continuity mistake: After Jack discovers the camera, we see what the camera is seeing in Howard's apartment on the screen. Where is Jack? He was just standing next to Annie. He should be front and center in the shot but he is nowhere to be found. The shot is wide enough that even if he was leaning out the door we'd still see him. When we see the monitor again later, he is there.
Continuity mistake: When Jack is under the bus there is a shot from the driver's side that shows the vehicle pacing the bus. The two people that were standing on that vehicle are gone. They are back the next time we see it (when the bolt snaps).
Audio problem: Annie is driving the wrong way down the street hitting cars. She starts mouthing "oh shit" but the audio suggests otherwise. She says "oh jeez."
Continuity mistake: When Sam gets shot, Annie takes the wheel back. We see the bus swerving toward the wall as Annie is grabbing the wheel. In the next shot inside the bus, she repeats the action.
Audio problem: After Sam gets shot several passengers are trying to help. One of them talks about how he's bleeding. Her mouth isn't moving.
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: When Keanu is pulling onto the freeway in his jeep, he starts honking his horn. The actor isn't pressing the horn in the wide shot. When we see Keanu from the front he is.
Continuity mistake: Payne has just forced his way into the subway car with Annie as his hostage. Jack shoots the lock off an emergency door in pursuit. The bullet holes on the two sides of this door do not match. (01:40:05)
Other mistake: When Jack and Harry are going down the elevator rope to the freight elevator, in the shot that shows Jack sliding down the ropes, you can see that the roof ends at floor 23 or 24, but there are supposed to be 48 floors.
Revealing mistake: When Jack is under the bus attempting to dismantle the bomb, if you look closely, when the cable comes off the hook, you get a shot of Norwood and the Lieutenant standing on the edge of the van holding the cable - you can see that it's their stunt doubles standing there.
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)
Revealing mistake: In the elevator scene, when Jack looks up standing on top of the elevator, you can obviously tell that he is in front of a rear projection. Notice the elevator ropes don't move one bit.
Other mistake: When the safety cable goes taut and stops the falling elevator, a woman standing in the corner is shown to fall through a hole in the floor. However, the hole in the floor was plainly visible in the bottom of the elevator as it was falling. As the hole was more than wide enough for the woman's legs to fall through, she couldn't have been standing in that corner as it was falling.
Continuity mistake: When the cops arrive at Payne's house, the front passenger door of the silver car closes. However, in the next shot it is open. (01:19:45)
Continuity mistake: When Helen tries to get off the bus, Payne blows up the door. The door is open. However, in the next shot, when looking over Jack's shoulder, the door is closed.
Continuity mistake: As McMahon watches Harry stumble out of the bar, he takes a puff of his cigar. Between frames, his right hand quickly moves from the cigar to the counter-top. (00:26:30)
Continuity mistake: When Norwood and McMahon break out their maps after hearing about the gap, their platform truck passes a large overhead freeway sign on the right, as seen in a rear window reflection. But a second later, when McMahon insists that the freeway is finished, the sign is roughly 100 yards away instead. (01:02:40)
