Character mistake: When the little girl is about to be blown away by the tornado she is crying terrified, but when she is swallowed by the tornado, spinning around violently, she stays totally calm, even bored. (Laserdisc and international extended editions).
Character mistake: The Daily Planet newspaper headline "New publisher for your favourite paper" has "favourite" is spelled the British English way. Since Metropolis is in the United States it should be spelled "favorite."
Answer: It was made on a very low budget. Golen - Golbus productions bought the rights to Superman. They were mostly known for B-Movies with not so big name stars. It was there attempt to play with the big studios. Plus at least 45 minutes of scenes were cut out, with major subplots.
In addition to budget cuts, they kept shortening the runtime, meaning scenes needed to be cut. The comic book adaptation has the uncut scenes and makes much more sense.