Day 2: 6:00 P.M.-7:00 P.M. - S2-E11
Deliberate mistake: When Jack and that FBI team are looking for Sied Ali in the mosque, Jack finds a burning body in another room. He is led to believe that it is Ali, because the body's clothes matched the description that Kate Warner had given him. It is obvious that the skin is badly burnt, yet the clothes are barely scorched.
Day 2: 8:00 P.M.-9:00 P.M. - S2-E13
Deliberate mistake: The blue and white airplane when the male terrorist tries to take off has the following registration: N34G5 This seems to be a deliberate mistake as only the following N registrations are officially possible: N plus one to five numbers (N12345) / N plus one to four numbers and one suffix letter (N1234Z) / N plus one to three numbers and two suffix letters (N123AZ).
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.