Visible crew/equipment: When Nina's just been shot, and makes it to the barn to call CTU (around 7.10am), while she's speaking on the phone there's a cameraman visible on the right hand side (DVD). (00:12:40)
Continuity mistake: When Jack stops at the bus station to get a bag, we see a shot of Jack's car from the point of view of the guy who has the bag. You can see a quite big camera inside the car on the left side. When we see the reverse shot from inside of the car, the camera is gone. (00:05:55)
Visible crew/equipment: Teri attacks Rick - the camera pans behind a pillar and the camera shadow can be seen on it. (00:20:35)
Visible crew/equipment: When we see Nina at the start (in the split screens) watch the bottom window and you will see a panning shot that swaps from her left side to her right. In this shot you can see the camera shadow across her back. (00:01:50)
Revealing mistake: Tony Almeida tries to phone with a telephone, which is not switched on. You see that the screen isn't displaying any information. (00:25:10)
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.