In the closing scene Eli's helicopter takes off as he is talking to Cameron. However, cuts back to close-ups of Eli during the conversation reveal stationary trees behind the helicopters starboard side.
When Eli pulls Cameron onto the crane, Eli's arm wraps around him and stays wrapped around him for the rest of Cameron's closeups even though Eli has removed the arm to tell Cameron to look into his camera.
In one of the WW1 scenes, a wall is painted with the names of two French towns: Verdon and Nancy. "Verdon" should be spelled "Verdun," which is not far from the French town of Nancy, and was the site of a famous WW1 battle.
One minute, Cameron is on a bridge in the town of Fair Oaks, California, and Eli Cross is in a helicopter observing him. Then, inexplicably, they're all in San Diego, California, over 100 miles to the southwest.