Continuity mistake: The clock on the bomb's secondary timer doesn't match with reality while Prentiss is trying to defuse it - going from 15 seconds to 10 too slowly, then skipping the final few seconds so it can end on 1 second remaining.
Factual error: While JJ and Will might have exchanged "commitment vows" with a willing officiant, they could not have actually married in the time frame given for multiple reasons. The bank robbery occurred on a Saturday and the proposal was that evening at the hospital, with a stated intention to go down to the court Monday to wed. Instead, Rossi and Will set it up for the next evening, which was Sunday. The following is taken from Washington, D.C.'s marriage information site: 1) the court offices that issue licenses are only open M-F; 2) there is a mandated three day waiting period between obtaining the license and performing the ceremony; 3) there is a ten advance notice required to arrange a civil ceremony through the court office. Therefore, the earliest they could be legally wed would be on Thursday with a license and a private ceremony, while a civil ceremony would actually have taken an additional week. As for JJ's "lets get married tonight", I can't see any hospital chaplain obliging.
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