- Adaptation Displacement: This film is probably better known nowadays than the short story it originated from. And this film is probably better known by many people as the film lampooned in Mystery Science Theater 3000: The Movie than by itself.
- Big-Lipped Alligator Moment:
- While the context makes it clear that the whole "plane turns green and lands itself" was the Metalunans saving Cal because they needed him, the whole incident has pretty much no impact on the plot and is never mentioned after the scene ends. (Lampshaded in MST3K: "I don't want to talk about it any more"). If you'd cut from Cal flying his plane to Cal arriving at his lab, you'd never notice that something was missing.
- In the uncut version, while building the interocitor, Cal gets a phone call from a mechanic explaining they couldn't find anything wrong with his plane.
- Ensemble Darkhorse: The Metaluna Mutant has a pretty short screen time and it became one of the iconic 1950's movie monsters.
- Retroactive Recognition:
- "Seinfeld" Is Unfunny: It was rather technically advanced for its time (it was Universal's first attempt at doing a sci-fi movie in color), its story was much more ambitious than most of its contemporaries, and it inspired quite a few creators (as evidenced by the number of Shout Outs it's received over the decades). That said, the genre has moved past it in almost every fashion (the sound still holds up), and it's much easier these days to appreciate it as kitsch rather than a serious genre film. The fact that it got lampooned in Mystery Science Theater 3000: The Movie doesn't help (even though the creators said that part of why this film was picked because they wanted to lampoon a good film for once).
- They Wasted a Perfectly Good Plot: An hour of setup, complete with competing viewpoints from Exeter and Brak, and once they get to Metaluna... it all becomes a "Point and shriek at the aliens" fiesta.
- Took the Bad Film Seriously: Not really a bad film, but Rex Reason (Cal) and Jeff Morrow (Exeter) are both a few degrees too intense in their performances. Morrow especially throws in all sorts of melodramatic tics in an attempt to put Exeter's Anti-Villainy front-and-center.
YMMV / This Island Earth