Elvis recorded it in 1971, on May 17 to be exact. I think if you would listen very close you would discover more of this mishaps. Sometimes he made a mistake and decided to record his vocals again but when it came to that he was not in the mood for any recording. So RCA used what they had, in this case with these mistakes.
Listen closely to "Indescribably Blue". Somewhere in the last part he starts laughing but managed to controll himself. I discovered that when I was listening to some of his home recordings. He's singing along with his recording of this song started to laugh about his laughing.