Deliberate mistake: When Eric Kriegler shoots in the biathlon, the camera looks from behind the target, through the holes of the targets he has already hit. But in the next clip it can be seen that little flaps fall down and cover the holes when they are hit.
Deliberate mistake: When "Henry Faber" discovers the phony airfield, several helicopters with Army markings are among the aircraft visible. Although the Army did use helicopters experimentally during WWII, those used bore no resemblance to those shown in the film.
Deliberate mistake: At the beginning, Alice turns on the tea kettle and it starts whistling less than a half a minute after it's turned on. It'd take alot longer. (00:10:00)
Deliberate mistake: O'Niel needs a sample of a dead man's blood to test for toxic drugs. So he visits the corpse, which has been dead for quite some time and is lying on its back, and proceeds to insert a hypodermic syringe into the dead man's frontal neck, extracting the sample. But blood pools low in the body soon after death. There ought to have been no blood available from that location of the body. To get blood, O'Niel should've punctured the corpse's underside.
Deliberate mistake: When Max opens the dog food, the lid should be all jagged because of the type of can opener he uses, but when dog and the gyro captain have the can the lid is cut smoothly. This was done so dog didn't get cut whilst eating out of the can.
Deliberate mistake: When they are listening to the tape, Cheryl yells out and shuts it off. Scott says he wants to hear the rest of it, but then deliberately fast-forwards it a bit before starting it playing. If he wanted to hear the rest of it, why does he skip part of it? This allowed Cheryl to shut it off as soon as she finished her line/action, but then Scott could fast-forward it past a mark on the visible reel-to-reel tape so it would start immediately on the chanting rather than in the middle of the lecture where Cheryl stopped it.
Deliberate mistake: When the scanners escape the apartment in the van and the assassins are in pursuit there is a street view shot of the assassins driving up next to the scanners' van. If you watch the street on the right side of the screen you can see people stood watching the filming in groups, out of harms way. (00:50:28)