Plot hole: The Unit discovers a soldier who they think is Betsy, tied to a chair. They note that the room is covered with PIRs or Passive Infrared Sensors. They then take out their night-vision goggles and begin counting the number of "infrared lines" they see. However, PIR sensors don't emit anything; they are passive. (00:23:15)
The Unit (2006)
1 plot hole in season 4 - chronological order
Starring: Robert Patrick, Dennis Haysbert, Audrey Marie Anderson, Regina Taylor
Continuity mistake: When Tiffy comes to visit Kim, the coffee mug she is holding changes between shots. In one she is not holding it to the ear, but in the next she is.