Character mistake: Both in the movie (and stage) versions, Mushnik makes a verbal mistake. Seymour shows Mushnik his new plant (Audrey II) for the very first time, but seconds later when the plant suddenly droops, Mushnik asks Seymour, "Why is it always wilting like that?" Always? He's just seen the plant! The line should be, "Why is it wilting like that?" Some smart stage directors of the play version have wised up and changed the line.

Continuity: When Seymour tries to kill the plant he pulls a gun, the gun is a six shooter, the plant grabs the gun and fires at the guy, then he fires some more, in total the plant fires 9 shots with a six shooter...

Factual error: When Steve Martin dies with the mask on, the inflation bulbs (the little black bags that inflate and deflate) deflate completely. Actually they should INFLATE completely and stay that way. The gas is still on full blast and Steve is no longer inhaling (which would cause them to deflate). It was done only to emphasize Steve Martin's demise but it's factually incorrect.

Audio problem: As Seymour's worries about Audrey II start to get worse, Audrey II says "You think this is all a coincidence baby, your sudden success around here, the press coverage?" Listen carefully to "the press coverage". This is a dub over of the original line "Your adoption papers" (this line also fits better with the mouth movement). Since Seymour wasn't adopted by Mushnik in the movie this wouldn't make sense for Audrey II to say.