Other mistake: At the beginning of the film a bomber is crashing. As this is happening another bomber is stationary in the sky.
Other mistake: When they are in the trench the other sub fires two torpedoes at them. The captain calls for right full rudder. They then show an underwater show of the sub turning left. After two more torpedoes are fired the captain orders left full rudder and they show the same underwater shot of the sub turning left.
Other mistake: When the parent monster is just about to enter Piccadilly square, for a brief moment a view of a bus is shown. The writing on the bus is reversed.
Other mistake: The puppies apparently can't see when Lucky puts his head in front of the TV. The first time we see him do this, he is barely covering anything, but the puppies claim they can't see.
Other mistake: When Regret, Jake, Pilar and her father are escaping from the Comanchero village, there's a close up of Jake (Wayne) in the back of the wagon shooting a rifle. The scene shows him shooting left-handed. It's a reverse print. Look at his "right" hand in the scene. He has a ring on his "right" hand ring finger. A few moments later, setting the wagon canvas afire trailing out the back of the wagon and shooting right handed, the ring is on his left hand as it is in the rest of the movie.
Other mistake: Brian Keith sneaks into an Indian encampment at night while they are sleeping. In order to stampede their horses, he rapidly fires the one and only six-shooter revolver he has into the air...eight times.