Continuity mistake: When the train driver passes out, several (speeded-up) shots of the tunnel and the shots of the bystanders on the platform show that the train is moving really fast, but in between there's a shot of Lois at normal speed, and the lights of the tunnel seen through the windows show that the train speed is quite low.
Continuity mistake: One of the general shots in the subway shows Superman flying slower than usual and inches away from the bystanders. The problem is that their coats and hair don't flutter nor do they notice him passing by or seem nervous in any way. However, the next close shot of their faces show them nervous and in awe at the action.
Continuity mistake: While Nuclear Man is destroying Metropolis, two police cars get moved backwards. The first shot of the cars moving show a lot of people by a shop window. The angle changes to a close shot, with no people there, then back to the previous wide angle, now with the cars moving backwards, and the bunch of people reappear.