Plot hole: Jacks talks into a cell phone when a helicopter lands in front of him - and the other side understands what he's saying. What a cell phone. (00:04:15)
Day 4: 12:00 P.M.-1:00 P.M. - S4-E6
Continuity mistake: Day Four: 12:00 PM - 1:00 PM. When Tariq and Behrooz are shown in split-screen digging Debbie's grave right after the commercial break (12:54:10 by the show's clock), Tariq's white t-shirt is covered in dirt. When the shot goes back to them a minute or so later, Tariq's t-shirt is much cleaner.
Visible crew/equipment: When Teri Bauer and Alan York are cleaning up the mess in the furniture store, you can see a mic moving on the left side behind a plant (while the camera is near the floor).
Day 6: 6:00 PM - 7:00 PM - S6-E13
Continuity mistake: When Logan walks into Martha's bungalow, there is a deliberate close-up of the photograph with Martha and Anya, in a narrow goldtone frame. Oddly, in following shots, that photo is in a wide width, white frame. Additionally, the arrangement of all the frames on that table changes quite a bit as well.
Day 6: 7:00 AM - 8:00 AM - S6-E2
Other mistake: At 7:45 Ahmed leads Scott out of his house at gunpoint so he can go to Scott's house. At 8:14 they arrive. But Scott's house is just across the street so we're supposed to believe that it takes half an hour to cross the street.
Day 2: 7:00 P.M.-8:00 P.M. - S2-E12
Revealing mistake: When Kate Warner phones her sister, Marie holds her phone up to the camera and you can see that the words "KATE'S CELL" have been written using the 'Write Messages' function on her Nokia. The 'abc' in the corner gives it away plus you can see the cursor trying to be hidden by being moved next to the 'K' (00:20:05)
Continuity mistake: In the police station, Kim's right arm is handcuffed to the bench as we see the profile/ master shot of her and Rick, but in the next shot, (the medium/front), Kim's right arm is behind her now and not cuffed, as Rick is being cuffed to the bench. A few seconds later, her right arm is again handcuffed to the bench. Kim's right arm is moving around as she talks to Rick and the scene progresses. Her left arm is finally uncuffed when the detective goes to book her. (00:06:20)
Day 4: 1:00 A.M.-2:00 A.M. - S4-E19
Plot hole: At 01:50 am, Chloe is told to go to Sabir's house. She arrives there approximately 5 minutes later, at 01:55:45. At 01:58, Jack is told that the closest tactical team is 15 minutes away from Sabir's residence. A few moments later, Jack mentions that the tactical team is 10 minutes apart from Chloe, meaning they bothered to send the team over there even though any officer currently at CTU HQ, including Jack, could get over there a lot sooner.
Day 4: 9:00 P.M.-10:00 P.M. - S4-E15
Factual error: The bad guy uses the thumb to access the Air Force base at the end of the episode. Thumb scanners are activated by the pulse and wouldn't work otherwise.
Day 4: 4:00 A.M.-5:00 A.M. - S4-E22
Other mistake: After Michelle and Tony kiss, he goes away and she says 'Tony, be careful'. In the next episode in the "previously on 24" section Michelle whispers it to his ear. (00:29:30)
Day 4: 11:00 A.M.-12:00 P.M. - S4-E5
Plot hole: Jack's CTU-car arrives only 1 min 20 seconds later after he has asked for it. Remember the time he needed from the store to the roadblock in the previous episode. The CTU-car has to be K.I.T.T. with a enormous turbo boost. (00:04:20 - 00:05:40)
Day 5: 9:00 A.M.-10:00 A.M. - S5-E3
Continuity mistake: During Episode 3 of Season 5, the terrorists take Derek in front of live television. When the terrorists force him on his knees, you can see a splatter of blood on the floor from the body of the last victim that was shot there. As time is running out, another shot of Derek being held by the terrorists is shown, and the mere splatter of blood that had been near his knees is now a noticeably big pool of blood. Nobody has harmed Derek yet, and there are no signs that he is bleeding. So where did all that blood come from?
Day 3: 1:00 A.M.-2:00 A.M. - S3-E13
Continuity mistake: When Jack leaves the cockpit he puts his gun away in a holster on his back. When he gets back to Nina and Chase he puts his gun away a second time.
Day 5: 1:00 PM - 2:00 PM - S5-E7
Continuity mistake: In the "Previously on." montage, Ivan Erwich tells Walt Cummings "Your country is about to pay a very steep price for betraying us." But at the end of the previous episode, Erwich never says "for betraying us."
Day 3: 7:00 A.M.-8:00 A.M. - S3-E19
Continuity mistake: When Kim is working undercover, dressed up in Saunder's daughter's clothes, she comes out of the Ladies' toilets wearing brown trainers. As she sits down at the library computer, you see she is wearing her very high heeled shoes. A few seconds later, as she is walking between the library shelves, she is wearing brown trainers.
Day 2: 6:00 A.M.-7:00 A.M. - S2-E23
Revealing mistake: After Kate Warner has picked up Kim Bauer, they are drving back to CTU in Kate's car. Unless I'm mistaken, when the car is shown, there is no number plate.
Day 4: 12:00 A.M.-1:00 A.M. - S4-E18
Continuity mistake: To get crucial information from Prado, Jack offers his resignation to Buchanan, and takes Prado on as a private citizen. But Jack doesn't work for CTU; he works for DOD, and is at CTU on a provisional basis.
Day 3: 7:00 A.M.-8:00 A.M. - S3-E19
Plot hole: How did they manage to strip Jane of her clothes and get Kim out of her own and into Jane's in the very short amount of time they did it in?
Day 5: 9:00 PM - 10:00 PM - S5-E15
Continuity mistake: Season 5 - 9pm-10pm, at 9:41pm. - Technical weapon error. When Jack takes the Federal Marshal's' Glock pistol, in an effort to add drama, he holds the pistol in his right hand and cocks it with his left hand by grabbing the slide, pulling it back, and releasing it to chamber another round. However, after he does this, the camera zooms in on the gun as it is pointed at Colette's' head and you can see that the slide is still back on the gun and NOT capable of firing at all.
Chosen answer: Nobody knew, not even the writers, until at least halfway through the season when they were writing the end. They wanted to keep all options open.
Nick N.