Continuity mistake: When Non lifts the cops' car, the fat cop starts to tuck his head inside the car, but a frame later it's already in, without having finished the movement.
Continuity mistake: In the big fight in Metropolis Ursa chokes Superman, but a frame later she is 3 meters away from him and her hands are off his neck.
Continuity mistake: Under the elevator when Lois says "Nobel prize" her fingers are completely black, covered in grease. When she starts to say "lil' o" they're just slightly dirty. When Superman saves her they're spotless.
Continuity mistake: Non attacks the guard, who activates an alarm on his belt. In the wide angle all of his left hand is on the alarm, on the close-up only the index finger. This keeps swapping back and forth.
Continuity mistake: When the villains are in front of the sheriff's car he places his hat next to the steering wheel. When the angle changes, the hat is away and he's repeating the movement.
Continuity mistake: When Clark and Lois land inside the ice cave, the wires holding her are visible.
Continuity mistake: When Superman brings the flag to the White House, the wide shot shows the wind stopping, and the flag coming to a smooth stop. Immediately after, in the close-up, the flag is moving wildly.
Continuity mistake: When Clark is lying beaten up on the diner floor, a man in a brown suit next to him disappears.
Continuity mistake: Before the villains arrive at the Daily Planet, Lois' hair is fluffy and her fringe has a straight cut. When the scene ends, her hair is shorter, and her fringe has some stylish cuts. Also, Jimmy's hair alternates between very short and long, due to Richard Lester's reshoots.
Continuity mistake: When Zod throws the shotgun after discharging it, it lands in front of the police car's back tyre. But when the dumb one goes to pick the gun up, it is now towards the back of the car.
Continuity mistake: When Zod is considering things on the moon, look at the shot of the Earth and the Sun behind him. First, there's apparently a lunar eclipse going on. You see the Earth on the Sun's right side. Then the camera pans over, and the Earth moves over to the Sun's left.
Continuity mistake: Before the East Houston scene, the rear view mirror in the cops' car is skewed in the outside shots, but straight in the ones inside.
Continuity mistake: Man in a yellow shirt disappears after Ursa stops the bus in Metropolis.
Continuity mistake: When Ursa says "your general wishes to speak" her right arm changes the way it's open.
Continuity mistake: After saving Lois in the river, Clark falls on the water and Lois cries "Here.", a split second later she has changed position, being now turned around and she has also moved 3 feet into water close to Clark.
Continuity mistake: When villains fly through Perry's window the reflection of the lights disappear and the blinds flutter without any problem, revealing that the glass was taken out to allow for a safe jump.
Continuity mistake: In the bar in East Houston, the man that challenges Ursa to arm-wrestle has his right arm and elbow on the table. In the next shot they're down.
Continuity mistake: When Ursa sits down to arm-wrestle, a man with a red jacket who was sitting several feet to the left, suddenly appears on the back close to the guy with a Coors T-shirt.
Continuity mistake: The watch on the left hand of the cop holding the binoculars while watching the Eiffel Tower, appears and disappears between shots.
Continuity mistake: When Ursa descends through the White House window, she is facing the back of the cop holding a gun. In the next shot she lands facing somewhere else, the cop now being by her side.
Answer: Superman was be able to kiss Lois in such a way that the heightened emotion wiped out her memory of his identity. To answer your second question, even though Lois promised not to tell anyone, Superman decided he does not want even her to know his secret identity.
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