Factual error: The train car in which Elle and the other passengers are held hostage is supposed to be an Amtrak type long distance railroad car traveling from El Paso to Dallas, yet on the inside of the car we can see a large poster showing the Washington, DC Metro system map.
Other mistake: When Morgan is showing the rest of the team the drivers license photos of the hostages on the train, every one of them is wearing the same shirt as they are on the train.
Character mistake: Close to the end of the episode, Dr. Reid says to the psychotic guy that was holding hostages, "M-theory cannot be proved." It should be "proven, " not "proved." Dr. Reid is supposed to be a genius, so he should be the last one to make such a mistake.
Chosen answer: Back in Target Rich, a hitman named Giuseppe Montolo dies whilst being interrogated by Derek. The men who abducted Derek were hired by his father, Chazz, who seems to blame Derek for his son's death. It's explained further in A Beautiful Disaster.
Annabel Keeley