When Senator Mayer enters his house, he switches off his alarm. Later, he walks into his office and we see Jack waiting for him. How did Jack get in without tripping the alarm?
When Agent Moss and his team assemble in the FBI office before going after Jack, you can see tape on the floor indicating where the actors should stand.
Senator Mayer: If you want me dead, Bauer, you will have to kill me where I stand.
Jack: If I wanted to kill you, Senator, you'd be dead already! Now take a seat!
Jack: Of course I have regrets, Senator. I regret losing my family. My wife was murdered because I was responsible for protecting David Palmer during an assassination attempt. My daughter can't even look at me. Everyday I regret looking into the eyes of men, women and children knowing that any moment their lives might be deemed expendable in an effort to protect the greater good. I regret every decision or mistake that I might have made which resulted in the loss of a single innocent life. But do you know what I regret the most? Is that this world needs people like me.