Continuity mistake: After Superman saves the train from derailing, there's a wide shot of the lead locomotive and it has just one small window on the side. In the immediate close-up there's a big window where the conductor peeps, and a sudden second window with a handle bar where another engineer shows up.
Character mistake: In the Air Force One scene, when lightning destroys one of the plane's engines, one of the pilots tells a co-pilot to inform Metropolis Airport that the president is on board the plane. The crew is unnecessarily repeating themselves: just a few moments before, they radioed in that "Air Force One" was on approach; the plane would only have that call sign if the president was on board.
Continuity mistake: When Clark first meets Lois and the staff of the Daily Planet, he is wearing a handkerchief in his suit pocket. After using it to wipe up the spill from the soda, he stuffs it loosely back into the pocket when he exits Mr. White's office. A couple of shots later, it is neatly folded back into a triangle. (00:53:15 - 00:54:15)