The Adventures of Mark Twain
"The Adventures of Mark Twain" (1986) was created by Will Vinton, known also as the animator of another rightly horrifying phenomenon, "The California Raisins." Contrary to all the hype on YouTube, it was neither banned nor a television show.
You can find the entire movie here — it's in three parts, and actually has a cohesive plot. I haven't gotten through it all, but I imagine the "Mysterious Stranger" scene (which, like everything else in the film, is based on Twain's work) is less of a bad drug trip in context.