Continuity mistake: Throughout the series when Megan Reeves is wearing long sleeves they tend to go up and down in split-second speed between shots.
Factual error: During the scene when Megan and the FBI are making the house entry, a scene cuts to two FBI agents, one with a M4 and another with a MP5. The agent with the MP5 has the magazine in his weapon installed backwards. (00:05:10)
Other mistake: The MP5 carried by one of the Federal officers breaching the meth lab has the magazine facing backwards.
Factual error: In one episode, there is a chase with the suspect driving an ambulance. The chase ends when the ambulance runs into and flips over a motionless taxi perpendicular to it, killing the suspect. There's no way this could happen, because at those speeds the impact would make the taxi flip over if anything.
Continuity mistake: Season 2 - Episode 16 - "Protest": Near the end when the guy is threatening to drop the nitroglycerin, he drops the test-tube and it lands on a red mat. However, when the agent picks it up, there isn't a mat anywhere near the test-tube.
All's Fair - S2-E18
Revealing mistake: In the scene where Don and the FBI crew is investigating the body of the Iranian victim, a split second closeup on the head of the Iranian woman shows she is breathing even though she's been dead for an hour already. (00:04:00)