Just before Lewellen is raped, when she is supposedly naked, a flesh-colored thin material can be seen covering her chest, just at the bottom of the shot.
Elvis Presley's appearance singing "Houndog" on the Milton Berle Show took place on June 5, 1956. Several of the vehicles used in the movie were newer than this. The pink Desoto (or Dodge) was probably a 1956, but it's not likely that a rural Alabama woman would be driving a new car. The tow truck used to tow the Desoto was a 1957 at the oldest, and it was quite beat up. The red Pontiac at the Elvis concert was a 1959.
The 45 rpm record that Lewellen's father gave her in the truck (supposedly by Elvis on RCA) is apparently a reissue of an original which did not exist at the time.