Although Elvis is the main character, not one piece of Elvis Presley music is heard in the film. Director Don Coscarelli explained that it would have cost about half the budget to license even one Elvis song for the movie.
Don Coscarelli:
[closing line]
The closing line of the credits, "...criminal prosecution and the wrath of Bubba Ho-tep," is a variant of "...and the wrath of the Tall Man" from the Phantasm (1979) films.
The filmmakers managed to round up about 100 extras for the Elvis concert scene, but as the filming dragged on, the extras steadily departed. By the end of filming, there were only a dozen or so extras left, which pretty much dictated which camera angles could still work.
The Texas license plate number, AZN-700, of the black Cadillac sedan used by the Memphis Mafia is the same as the red Cadillac convertible driven by Elvis himself.
Elvis: Where'd my youth go? Why didn't fame hold off old age and death? Why the hell did I leave the fame in the first place and do I want it back, and could I have it back? And if I could, would it make any damned difference?