It might have just been a cover. I had a large collection of those silver age Superman comics, and the covers always had the most ridiculous premises that the inside story was never about.
That always pissed me off so much. They'd show what looked like the climax of a fight, and the whole issue would just be rising action. And it's not like I could buy every issue; it all came down to luck.
If the new movies really want to recapture that nostalgia, they should make a wildly inaccurate trailer with a "to be continued..." at the end. Don't even call it Part 1.