Accidentally-Correct Writing: Yuggoth was meant to be a fictional ninth planet but Pluto was conveniently discovered when the book was being written. Lovecraft decided they were the same planet and mentioned Pluto's discovery in the story.
The film
California Doubling: Averted with location filming in Vermont and Massachusetts (with Mount Holyoke College as Miskatonic University).
Science Marches On: The Mi-Go use their wings to fly through the 'aether' of space; they can also use them (less effectively) in Earth's atmosphere. The film instead has the Mi-Go using mechanical wings strapped to their backs, and the advance party making the journey via spacecraft so they can open a 'spirit door' to their planet so the invasion force can come through.
Other versions
Mind Screw: A 2021 one-man play adaptation in New York City presented the story as Wilmarth presenting his findings to a local paranormal society (represented by the audience). Toward the end, though, a disembodied voice began suggesting Wilmarth was perhaps really locked up in Arkham Asylum, or was even imagining the whole thing after having been converted into a cylinder the same way Akely was. Several audience members really leaned into the chance to suddenly play malicious apparitions, laughing at Wilmarth as he begged them to assert they were real and he wasn't crazy.
