When Jack's secretary asks her boyfriend to lend her his phone while he's playing bass guitar in a live band, he has to stop playing to get the phone out of his pocket but the bass line in the music continues uninterrupted.
When Jack starts his secretary's car, his left hand is on the steering wheel while his right hand appears to remain on the center console, somewhere around where the emergency brake or gearshift would be on a car with a standard transmission.
When Jack's in the cabin, he crashes through a window covered with plastic. The sound of shattering glass is clearly heard, however if you look at the window after he's gone through it there is only the plastic, there is no glass.
When Jack logs into the router to filter the attempted hack coming from multiple countries, he creates an access list which only would filter a few addresses and allows everything else. His cohort's expression of "That would even eliminate false positives!" is fully false.
When Harry answers his cellphone when in bed, its a cam-shell/flip-phone, but he answers it, and holds it to his head without opening it, even though you hear the sound of the flip opening when the phone is out of the camera view.
When Jack and his secretary are driving to the cabin, Jack is driving with the secretary in the passenger seat, it then shows from a wide shot them crossing railroad tracks, the wide shot shows the girl is driving
When Jack is driving with his secretary following the dog tracker, they turn right with the railroad tracks facing the drivers seat. But when he leaves her and walks off the car is facing the right and the railroad tracks are on the side of the passenger seat.
When Jack and his secretary are driving through the rain the dialog continues as they're looking through the windshield and there are no wipers going. Next street shot shows rain pouring down as before.
When Jack is driving to the cabin before running over the robber with the gun, the drivers window is almost all the way down, but after he hits him, and the car is about to explode, the window is all the way up.
When Jack is driving his Chrysler to work early in the film, his steering wheel clearly has the shiny wooden insert/top featured in the more expensive models. Later in the film, he is seen driving behind an all leather wheel which shows no reflections.
When Jack exits the elevator at the beginning of the movie, we see what he sees through the pen's camera. We see a Dell USB keyboard attached to a computer. However, when the "real" camera pans to follow Jack around the bank he works at, the same keyboard magically becomes a multimedia keyboard, which the bank wouldn't be using anyway, because they use the card reader in the USB keyboard to read their employer's IDs.
When Jack Stanfield is in the process of sending the money he robbed to Cox at the wire transfer terminal, he secretly uses Bobby's cell phone to take a picture of Cox's account numbers. When the camera gets up-close to the cell phone, Jack's fingernails are short... quite short. But minutes later, when Jack inserts the virus disc into his office computer's optical drive, his fingernails are at least 3 mm longer.
After Jack gets to the house by the water, he's in a fight that catches a car on fire. Burning tires produce a lot of thick black smoke. But after he rescues his family, as they are walking away from the house, there is no smoke rising from where the car should be.
When we first see Janet's car (a fairly pristine Green 1970's Dodge Dart)it is more or less perfect. All lights work and it's in great shape but when Jack lets Janet out on the dirt road (to call the police) before driving to the old cabin/house both head lights are completely gone and the grill is broken. Then just a few seconds later when Jack drives over the bridge the car's headlights are back but the grill is partially missing.
The address on the account for the dog's tracking collar shows a Medina, WA address. The only body of water that Medina, WA is next to is Lake Washington. The house that is filmed throughout the movie is clearly shown on the edge of tidal waters indicating that it is not a Lake Washington waterfront home but next to the ocean (or Puget Sound).
(at around 58 mins) Jack has taped his makeshift scanner near the bottom of the monitor, and the data appears and scrolls from the top of the monitor. The first 20 or so largest accounts never pass in front of Jack's taped-on scanner.
When Jack goes to the bank at Seatac Airport to authorize the "reverse" wire transfers he would not be able to authorize a "reverse" wire from the bank where he was at. Only the bank where the funds originated can authorize a wire transfer to another institution. Secondly wire transfers do not happen instantaneously as depicted. They have to go through the Federal Reserve. It was late at night in this scene and the Federal Reserve closes at 6 p.m. EST. In Seattle that means that any wire originated after 3 P.M. would not have taken place until the next business day and even then could have taken up to 2 hours.
When Jack removes the memory card from Bobby's phone, the phone is still turned on. This would not cause data corruption if the card isn't being accessed at the time as the vast majority of memory cards are hot swappable.
The car the secretary drives is an automatic; when she stops the car in front of Bobby's church, she firmly pushes the gear lever into "park" which makes the car lurch. If the battery is dead on an automatic, you cannot start it by pushing.
When starting the secretary's car Stanfield says to pop the clutch which then starts the car. However, several times later the car is seen being put in Park. On a manual-transmission car that has been started by popping the clutch - as her's was - this would cause the engine to die, yet the car keeps running every time.
When Jack is driving to work at the beginning of the movie, a radio traffic report states that it is morning, but the Seattle skyline is shown sunlit from the west, indicating it's actually late afternoon.
The goof items below may give away important plot points.
When the secretary dialed 911 at the end of the movie, the tones are reversed. The tones that were dialed were 299, 599 or 899. One lower tone followed by 2 higher ones. In reality, it should have been one higher tone followed by two lower ones.
When Sarah, Beth and Andy Stanfield flee the lakehouse as Jack kills Pim and Cox, their hands are still bound behind them. After Cox dies, they return and are unbound with no explanation. It is later established that they did not meet Janet during this time.
When Jack enlists the help of Janet the secretary try to find his family, they "Push-Start" her car and Jack tells her to "pop the clutch." Later, after Jack drops Janet off by the roadside and tells her to call the police, he takes the car toward the lake house. When he stops there, we hear the sound effect of an automatic transmission shifter being moved quickly from "drive" to "park."
When Janet calls 911 after Jack and her have tracked down Cox and Jack's missing family, Janet is using a cell-phone. There are only three beeps, which in reality, should be four, because not only did Janet dial 911 (three digits,) but she would also have to press the green button for the phone to dial, which usually makes another beeping noise.
When displaying some console screens, there are quite often extra spaces in the commands. For example, when the display shows Jack mounting the bank transfer CD, the command "mount /dev/cdrom /mnt/cdrom -t iso9660" has become "mount /dev /cdrom /mnt /cdrom -t iso9660". The command to run the bank transfer also has these extra spaces "/mnt /cdrom / script".