Revealing mistake: Throughout season 2 on several occasions it's clear that John Terry (Bob Warner) is wearing a fake mustache and a fake beard.
Day 2: 12:00 Noon-1:00 P.M. - S2-E5
Revealing mistake: The Fox news video that Palmer watches of the Ambassador's helicopter being shot down is marked 1:18:24 in the lower right hand corner. The episode is supposed to take place between Noon and 1 p.m. This is 41.47 into the episode.
Day 2: 5:00 P.M.-6:00 P.M. - S2-E10
Revealing mistake: Right after Kim Bauer and Miguel start a fire in the police van, the vehicle swerves off the road and tumbles. In the next shot, you see "Kim" on top of the car, trying to get in through the window (the car is about to fall off a slope or something). Pay close attention, zoom in, or whatever, the woman is not Kim but is a stunt double. She's got a much chubbier-looking face and is definitely not Kim Bauer. This occurs at 19:40 in this episode. (00:19:40)
Day 2: 5:00 P.M.-6:00 P.M. - S2-E10
Revealing mistake: Kate Warner holds a bloody towel to her wounded earlobe. She puts it away and you can see a very clean band aid around the lobe. (00:27:55)
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)
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 2: 6:00 A.M.-7:00 A.M. - S2-E23
Revealing mistake: When Michelle is in the van, waiting for the computer to finish analysing the conversation between Alex Hewitt and Sherry Palmer, the computer bleeps to says it has "heard" enough of the conversation to be able to recreate Hewitt's voice. How ever, it bleeps whilst Sherry is in the middle of talking. The computer should have made the noise about 15 seconds before.
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.