The film provides examples ofnote tropes from the original stage production can be found on its page:
Adaptation Distillation through Pragmatic Adaptation: The subplot about Mr. Mushnik adopting Seymour is dropped, along with a few incidental songs, to make a tight 90-minute narrative. Also worth noting, the scene with Bill Murray as a masochistic dental patient did not appear in the stage version. It derives from a famous scene in the 1960 movie which originally featured Jack Nicholson in this role. Additonally, the Dragnet-parodying cops Joe Fink and Frank Stoolie of the original film are more or less entirely dropped from both musical versions, although they are briefly seen conversing with Audrey before the film's "Suddenly, Seymour" scene.
Adult Fear: It's hardly a coincidence that "Skid Row", a song about poverty and working-class depression, features a shot of Seymour slowly backing away in horror from a bunch of homeless alcoholics climbing a fence to get at him.
Apocalypse How: The Audrey II invasion as depicted in the original ending could potentially range anywhere from Class 0 to Class 5.
Award Bait Song: "Mean Green Mother From Outer Space" is not present in the stage version, although it has been added in some revivals. It was added to the screenplay so the film could receive an Oscar nomination for "Best Original Song." It lost, sadly. (It should be noted that "Mean Green Mother From Outer Space" is definitely not your typical Award Bait Song.)
Better Living Through Evil: Audrey II uses this method to convince Seymour to feed it Orin and Mesnick by bringing up the fact that it could make Seymour rich. It eventually works once Seymour realizes what he could buy with the insane amount of money Audrey II is capable of bringing in.
Karma Houdini: Seymour killed two people (he let Orin die despite making it clear that he could have helped him and he backed Mushnik into the plant) and considered going even further (he signed the contracts in "The Meek Shall Inherit", implicitly agreeing to kill others in the future. This is made clearer in the play where the song is extended, but the actions remain the same in the film.) but he gets away with absolutely no punishment whatsoever-Audrey likely never even learns that he is a murderer. Audrey II is a Karma Houdini in the original ending as well, but that is treated as a Downer Ending rather than a Happily Ever After, so that would be a case of They Plotted a Perfectly Good Waste.
It can be argued that Seymour finally standing up to and destroying the plant thus preventing the destruction of the human race pretty much makes up for the world being less one sadistic dentist (which WASN'T his fault, despite intentions to the contrary) and one greedy, albeit somewhat kind, shopkeep (which may not have been entirely on purpose whatever the plant said). Both deaths are made a lot more ambiguous in the film than the play, and can be interpreted as due to Seymour's actions or not.
The original ending makes it pretty clear that he didn't get away with anything, even if you don't count his death. Orin and Mushnik died only because Seymour doesn't prevent their deaths, and they both would have harmed him (Orin with dental sadism, Mushnik through blackmail) even if he had saved them. Audrey, on the other hand, he consciously fed to the plant, even if it was at her own selfless request. If he hadn't done it, Audrey II might not have been strong enough to tear down the building and eat Seymour whole.
Mood Whiplash: When you see the original ending, it can be hard for some to believe they were going to brand this movie as a comedy- The ending seems so much darker than the rest of the film that it's almost ridiculous. After Audrey dies in his arms, a distraught and pessimistic Seymour dashes out of the shop and is about to commit suicide off of the roof of Audrey's apartment complex when Patrick Martin finds him and tells him about taking cuttings from Audrey II. Poor Seymour then confronts the plant, but is instead trapped inside the shop as he tries to get away, helplessly tries to stop the plant with various non-working weapons, and has his goddamn pants pulled down before getting slowly and gruesomely swallowed whole by the plant all to the tune of an upbeat villain song. The movie then ends on a not-so-happy note with various shots of humongous Audrey II plants attacking the earth.