the most unrealistic part of the show was the total lack of traffic in Los Angeles
Every single time on 24 that someone needed to drive somewhere in LA you would never see them stuck in traffic. They were always able to get wherever they were going within a relatively short amount of time, always less than an hour. It wouldn't matter where in LA they were going to or from or the time of the day. Whether it was Jack Bauer, someone else from CTU or a terrorist, they never had to deal with traffic.
As everyone who has ever driven in LA knows, that's completely unrealistic.