The movie description of Who Framed Roger Rabbit has a line:
Keeping an eye over his shoulder, Eddie heads down some darken stairs.
None of the dictionaries I consulted list darken as an adjective. "Darkened stairs" doesn't sound right either, and the audio doesn't sound like it. So is "darken" used as an adjective? I am putting the audio clip here for reference, uploaded to a Clyp, an audio sharing site.