First, I want you to check out how EXACTLY this is the same movie as Airplane!:
I must have seen Airplane! maybe ten times, and I had no inkling that it was so directly satirizing this obscure movie. When Airplane! came out, it was a revelation. The world had never before seen a film that had so many gags per minute. Mel Brooks has talked about how it changed everything for comedy movies -- post-Airplane!, the pressure to cram in more comedy per second became intense, and if you didn't, your movie looked old-fashioned and out-of-date. When Airplane! came out, it was truly a wonder -- how could they have such structure, and be so zany? It was unlike anything I'd ever seen. Now the secret is obvious -- they were able to have both insanity and structure by completely borrowing the structure from Zero Hour! I don't think this diminishes the film in any way, but it gives some hint to what makes for good comedy.
Interestingly, I made a similar discover about another, similar film: Mel Brooks' 1974 film, Young Frankenstein. Again, I had assumed that this comic masterpiece was a completely original take on the 1931 Frankenstein. I was shocked to sit down and watch the 1943 Frankenstein Meets the Wolf Man, and realize that Young Frankenstein is very much a satire of that much lesser known film, in which a man afflicted with lycanthropy seeks out Doctor Frankenstein's castle, with a hope of curing himself. Sure, there's no Wolf Man stuff in Young Frankenstein, but the rest is all there. Some of the dialog, much like Zero Hour! / Airplane! is also a direct lift into Young Frankenstein. Also notice this... Airplane! came out 23 years after Zero Hour!, and Young Frankenstein came out 28 years after Frankenstein Meets the Wolf Man. Maybe that's just coincidence, but it would seem that there is a certain amount of comedy magic in making a strong parody of something that is 25 years behind you. That seems to be the same formula that both Happy Days and That 70's Show used.
I know -- this makes me seem nuts, and I probably think about this stuff too much. But I like to think this happened: In 1966, Woody Allen made What's Up, Tiger Lily, where he overdubbed a Japanese film. Mel Brooks saw it, and said, "That's kind of funny, but it could be much stronger", and reached back to the 40's to grab Frankenstein Meets the Wolfman and used it to create Young Frankenstein. Zucker, Abrahams, and Zucker surely loved that film, and thought back to their childhood about the ridiculous Zero Hour!, and used that to make Airplane!
Creative process is a secret thing -- but every time I tease out someone else's, it gives me more confidence about my own.