Revealing mistake: When Zod takes the rifle out of the cop's hand the strings moving the rifle are seen, each by the side of the cop's cowboy hat when the rifle turns red.
Continuity mistake: The coat hanger in Perry's office disappears between shots.
Continuity mistake: Non smashes Perry's glass but a second later the glass is back in place.
Continuity mistake: In the Fortress of Solitude, when Non is (green screened) flying towards Superman, Ursa and Lois disappear.
Continuity mistake: When Clark and Lois land inside the ice cave, the wires holding her are visible.
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.
Revealing mistake: The 3 villains break through the Daily Planet window and fly around the city. Before Zod stops by a beam, Non becomes transparent.
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.
Revealing mistake: After the Marlboro truck scene, Superman throws Zod and he goes through an office window. The harness to make him fly is visible on his back.
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.
Audio problem: In the Fortress of Solitude, when Superman kneels before Zod, we hear Lois sobbing, but her mouth and body don't move.
Deliberate mistake: French officers and firemen speak in English between them.
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: Inside the bar in East Houston, Zod pushes a man backwards, but the next shot shows the man flying as if he had been thrown upwards.
Continuity mistake: When Superman lands by the truck there are no people behind him. In the next shot there are a lot of people running around behind him.
Revealing mistake: When Ursa blows the helicopter away, the string holding it is visible.
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.
Matty Blast