Dead End (lost zombie comedy film; 1985)
During the 1970s and 1980s, zombie films were very popular. Films like Dawn of the Dead and Zombi 2 were successful moneymakers. While many independent zombie movies appeared over the years (such as Shatter Dead and I, Zombie) one simply just disappeared without a trace. This film was 1985's zombie-splatter-slapstick-comedy Dead End. The film, directed by Emerson Bixby (son of famous television writer Jerome Bixby, known for Star Trek and The Twilight Zone) concerns a documentary filmmaker going out to investigate a UFO crash, which in turn causes your basic zombie apocalypse. The movie reportedly features real animal blood and guts taken from a local slaughterhouse, which apparently caused one (or several) crew members to vomit and get sick.
According to director Bixby himself, his own personal copy of the film was lost in 1987, and he has since lost contact with cast and crew members, who may or may not possess their own personal copies. One person on the IMDb message board for the film claims that they saw a vendor at an early 90s horror convention selling bootleg copies; additionally, there are reviews on the site (albeit only 2), which means it does/did presumably exist in one format or another. However, until a copy surfaces, we will have no real proof.