In one scene, Callen mentions that he was shot on May 5th. This is actually the airdate of "Legend: Part 2", the NCIS crossover episode in which Callen's shooting happened. See more...
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NCIS: Los Angeles (2009) - 3 mistakes in entire show
Continuity: Episode 1-7, "Pushback": At the beginning a person is shot in the back of the head during a surveillance. The camera is filming a man and a woman on a boat at a marina. The feed is being played in real-time on the laptop. The killer starts to gather all the recording equipment, including dismounting the camera off the stand. The killer called the man on the boat to say "it's done". The computer screen shows the man on the boat leaving the boat even after the camera was dismounted.