Trivia: Jack's opening monologue changed subtly as the season moved on. It began, "Right now, terrorists are plotting to assassinate a presidential candidate, and my teenage daughter is missing." It then became, "...and my teenage daughter has been kidnapped," then "...my wife and daughter have been kidnapped," then, "...my wife and daughter are in danger," and finally, "...my wife and daughter have been targeted."
Trivia: We get the impression from the first few episodes that Nina is trustworthy only to find out in the last 2 episodes that she was the main mole inside CTU. It's funny though that it was in front of our eyes the whole time, by accident or design: Every time that Jack says his famous starting monologue, when he comes to the part "and people I work with might be involved in both..." we see Nina looking at Jack.
Trivia: Both Sarah Clarke and Xander Berkeley have played turncoat government agents assisting terrorists attempting to assassinate the President. Clarke on 24, and Berkeley in the film Air Force One, when the President interferes with the terrorists' insidious plan. Ironically, the pair began dating during season one, and by season two, they were married.
Trivia: After coming up with the concept of a story taking place in real time over the course of one day, Joel Surnow and Robert Cochran originally planned on the show being about the 24 hours leading up to a wedding. After realizing that it would be difficult to think of reasons for a bride and groom to be forced to stay awake for 24 straight hours, they decided that the show could instead be about a federal agent being forced to protect a politician from assassination for 24 hours - which became the plot of season 1 and the basis for the show.