While Callie is folding her father's clothes, the shirt in her hands changes from red-and-white plaid, to yellow, then back to red-and-white plaid.
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.
During the opening newsreel footage, the subtitles say that it is the discovery of the tomb of Amen Ho-Tep, but the voice over is explaining that it is the discovery of Tutankhamen's tomb (the sarcophagus shown is also that of Tutankhamen).
The voice-over narrative of the German newsreel at the beginning does not correspond with its English subtitles, the latter only serving as a tool to play into the movie's story line. At no point in the German V.O. is the "strange discovery of the tomb of King Amen Ho-tep" mentioned. Furthermore, the newsreel is actually a disjointed collage of several newsreels on different unconnected archaeological discoveries in Egypt.
There are no mountains (as seen in the Nacogdoches fair scene and Mud Creek) in East Texas.
Elvis is unable to prove his identity after being subjected for years, on a routine basis, to invasive medical examinations which would have revealed, even inadvertently, telltale identifying clues in blood, DNA, fingerprints, and other factors. (This assumes that he really is Elvis, which the film strongly implies is indeed the case.)
In the bathroom the boom mic is visible in the mirror behind Jack. It is most noticeable when he turns his head and the boom moves to follow.
The sign outside the front of the Shady Rest Convalescence Center in Mud Creek is misspelled "Convalesence Center".