The 1960 mystery Scent of Mystery piped 30 odors through vents beneath theater seats. Reviews complained of hissing, weak delivery, and scents arriving after the action. Producer Mike Todd Jr. later admitted the reverse pump needed to clear each smell occurred to him only after the premiere.
Sources: Smithsonian Magazine on cinematic scent systems; AFI Catalog: Scent of Mystery.
Illustrative image: Gmhofmann / Wikimedia Commons, CC BY-SA 3.0.