During the phone conversation between Jax and Gemma, while the opening credits are rolling the length of Gemma's cigarette keeps changing throughout the scene from freshly lit to half smoke and back again.
When Abel is having surgery, the heart monitor shows a rhythm called asystole. This means there is no electrical activity in the heart (assuming the ECG leads are connected to the patient). This rhythm is not considered to be a shockable rhythm, therefore the use of the paddles is inappropriate.
John Teller's headstone lists his rank as Corporal. On US National Cemetery headstones, his rank would correctly be shown as CORP.
Originally, Scott Glenn was supposed to play Clay Morrow, and filmed several scenes of the pilot. After Ron Perlman replaced him, most of the scenes were re-shot, but in some of the scenes where the motorcyclists are lined up, have Glenn in place of Perlman.
At 06:45 the line "Some yuppie creamed it out by the streams" is said supposedly by Tommy Flanagan's character "Chibbs", the voice over is not Tommy's voice.