Continuity mistake: After Sydney learns that SD-6 is not part of the CIA, she goes to Taipei. Just after she arrives, she takes a man's car. At this point the number plate reads DH 5578, but, in the next shot, as she is driving away, it is JU 1587. (00:51:15)
Revealing mistake: When Syd's Dad rescues her in the car park, he starts shooting at the other car. After firing one shot the slide of his gun locks back (indicating it's out of bullets), but when the angle changes he carries on firing with no problems. (00:43:20)
Continuity mistake: As Anna approaches Syd in the middle of the field, she reaches her hands up to her belt. In the very next shot from behind her, her arms are by her sides. (00:38:10)
Continuity mistake: Between the pilot episode and the second episode of Season 1, the swing of the blast door on the secret base reverses. In the pilot, the hinge is on the right and it opens from the left. In episode two, the door opens from the right with the hinge on the left. (00:12:05)
Answer: Bad Day by R.E.M.