In many episodes in season one, you can see cameras on stands and men walking carrying them, such as when Nina is in the abandoned building in the construction site. Or when Jack is walking through the basement of the building where Senator Palmer is holding his breakfast meeting.
Many of the agents (not including Jack, who carries a H&K type pistol most of the time) carry Glock manufactured pistols which do not have external safeties or hammers but throughout the series, you can hear them either cocking a hammer back or dis-engaging a safety.
Over the course of the series, several characters have speed dialed CTU on phones that did not originally belong to CTU or any other govt agency. Many times, they press a single button on the phone and the speed dialing sound effect is played.