Late one night during principal photography in Burbank, California, an older woman living near the filming location came over to writer 'Paul Tibbett' and demanded she get compensated. She complained that the electrical currents being created by a portable generator were making her "teeth loose".
The opening cow levitation sequence appears long in the film because credits were planned to be superimposed over it. However, the production ran low on money, so lower cost end credits were added at the close of the film.
The song "Secret Lovers" (which plays during the montage of Dorman showing Alien what "earths all about"...) was originally composed for Billy West to sing as a Frank Sinatra style vocal tune. However, scheduling conflicts prevented West from recording the track and it got produced as an instrumental.
Although William Val plays Leslie, the Chumley chauffeur, Fess Parker supplies his speaking voice.
An entire short film entitled "Painting With Pesion" was shot for the sequence when "Alien" watches the black & white painting show on TV. Created and directed by Conrad Vernon, this is the excerpt we see on screen. However, to keep the editing of the film fast, what ends up on screen is only Vernon's voice (as Pesion) and a brief simple shot of one of his epic paintings: a cow.