Where No Fan Has Gone Before
Season 4, Episode 11

The title to that Popplers episode is a reference to the Star Trek episode The Trouble With Tibbles, and this episode goes on better, casting some legendary Stark Trek actors – Leonard Nemoy, William Shatner, Walter Koenig, George Takei, Nichelle Nichols – as themselves A deranged fan is holding their disembodied heads hostage, see, so the gang step in to save them. We’ll leave you to see if they live long and prosper.

The Sting
Season 4, episode 12

What a strange episode this is. The Planet Express crew are dispatched to collect honey from a giant space bee honey colony, but Fry is shockingly impaled by a massive bee stinger and dies. This causes Leela to have all manner of bizarre, grief-stricken hallucinations. The resolution is a bit “it was all a dreeeaaam”, but it’s the journey there is hella fun and the episode is commendably odd.