Oh good Lord. I'm just flabbergasted by some of these reactions to the movie's Smallville setting. I never realized how important it was for many view "Superman: The Movie" as flawless or near flawless until now. Wow.
That's a needlessly condescending reply. Nobody claimed
Superman: The Movie is flawless or near-flawless.
The most obvious flaw to
Superman: The Movie is that it (like many superhero films to follow its lead in the decades to come) kind of falls apart in the final act. The conflict that Ghost Jor-El presents Superman with, that it is forbidden for him to change history to save Lois, is arbitrary and unmotivated; the idea that our hero must chose between his Human and Kryptonian identities works on a thematic level, but there's not plot device to rationalize it. And then, after Ghost Jor-El has warned him about dire consequences from changing the past to save Lois... nothing happens. There are no consequences.
(A similar problem is present in
Superman II, when we are told Clark can never become a Kryptonian again after turning Human... and then he turns back with no explanation and no cost.)
Structurally, the villains are insufficiently weighty. Gene Hackman is of course compelling as a performer, but his Lex is essentially a generic James Bond-type villain motivated by blind ego. Ned Beatty's Otis is a problem -- I liked him a lot when I was a little kid, but he's the most overtly "little-kid" character and he's just too broadly-played and broadly-written. And nothing about Miss Teschmacher's motivations make sense. She's clearly not living in great wealth, she clearly doesn't have feelings for Lex, and she doesn't appear to be trapped in an abusive relationship.
Anyway, moving back to the Smallville scenes -- saying that the anachronisms are deliberate is not the same thing as saying that they are without flaw. I'd say the biggest, most obvious flaw to those scenes is that Martha Kent doesn't get nearly enough narrative attention; Jonathan and Marth are obviously both more archeytpes than they are fully-fleshed characters, but Martha's role is particularly two-dimensional.
But the idea that the anachronisms were unintentional just seems absurd to me. These people knew fundamental math. They knew someone born thirty years ago would have been in high school twelve years ago. This wasn't a mistake -- it was deliberate. Maybe it didn't work for you, but that doesn't mean they made the choice out of ignorance of basic math.