Just before jumping into the water to rescue Nina, Cameron is already all wet.
When Cameron previews the footage of Bert's demise, the windshield has no hole in it, then a hole appears as they look at the footage, but then it's missing again in the next shot.
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.
At dinner, after Eli's line "This film... is not about fighting wars, Sam," Sam's right arm jumps; first it is putting some food in his mouth and then it's resting on the table.
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.
The car used in the main "driving off the bridge" scene is consistently described as a Duesenberg, but it has the well-known Mercedes-Benz hood ornament.
Throughout the movie, Peter O'Toole says that King Kong was three foot six inches tall. The real clay model of King Kong in the 1933 movie was 18 inches tall. Of course, this adds to his point: you cannot accept anything in the movies as fact, including this quote.
At the company dinner, Peter O'Toole puts his fork into some food but when he puts the fork in his mouth there is no food on it but acts as if there was. Actors avoid eating food or else will take very tiny bites to avoid becoming full with repeated takes.
During one of the battle scenes, an actor portraying a German officer in a machine gun nest orders food on a field telephone: "Achtung, bringen Sie mir etwas zu essen!" (Attention! Get me something to eat!).
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.